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On occasion, SWGDAM will use this page to post responses to frequently asked questions from the forensic DNA community or other interested parties for the purposes of general information. The intent of this page is not for it to be a comprehensive list of answers to all of the inquires SWGDAM receives, but rather a collection of those inquires that SWGDAM recognizes to be of interest to a broad spectrum of forensic DNA science practitioners and/or consumers. 


SWGDAM recognizes that not all inquires will be amenable to the short answer format of this page and will continue to use its members, meetings,, and conference updates to collect and disseminate information.


Please note that some questions have been edited for brevity, clarity, and/or to remove specific identifying information. Text contains within [ ] indicates information added by SWGDAM.


SWGDAM Y-STR Interpretation Guidelines

QUESTION:  Our laboratory utilizes a direct-to-DNA approach for the analysis of Sexual Assault Forensic Evidence (SAFE) Kits, where qPCR is used to screen samples for the presence of male DNA (Y-screen).  We have dedicated personnel who extract and perform qPCR on evidence samples from these kits, interpret the results of the qPCR, and issue a report containing the results of the Y-screen.  These individuals do not perform any other aspect of DNA analysis.  After the completion of the Y-screen workflow, either the SAFE kit swabs or the already-prepared extracts are forwarded to a separate section of the laboratory for autosomal or Y-STR analysis, as appropriate.  Are the individuals performing the Y-screen workflow subject to the DNA analyst requirements of the QAS?


SWGDAM Response: Yes.  Individuals who interpret Y-screen results and/or prepare reports are considered analysts under the QAS and are bound by all applicable requirements, including but not limited to those requirements related to education, training, experience, and proficiency testing.  In this scenario, individuals who extract and perform qPCR, but do not interpret the Y-screen results or prepare reports, are considered technicians under the QAS.


QUESTION:  What if the Y-screen extracts are discarded after qPCR and are never used for STR analysis? 


SWGDAM Response:  Even if the extracts are discarded after performing the Y-screen, the individual interpreting the qPCR results and/or preparing a report is considered an analyst and subject to the QAS requirements as described above. 

SWGDAM recognizes the need for further clarification on the application of the Quality Assurance Standards to Y-screening workflows and a SWGDAM Communication is currently in progress.  In the interim, proficiency testing requirements related to qPCR workflows can be found in the SWGDAM Clarification on Proficiency Testing of qPCR Workflows Including Y-screening. 


QUESTION: I am hoping you can shed light on YFiler Plus…regarding the update of the statistical calculations for the US Y-STR database. Prior communication…indicates that there [is] insufficient YFiler Plus data available to perform empirical theta calculations. Based on the current data available, can the statistical calculation be updated for YFiler Plus?

SWGDAM Response:  The SWGDAM Interpretation Guidelines for Y-Chromosome STR Typing by Forensic DNA Laboratories -Approved 01/09/14 recognize that population substructure exists for Y-STR haplotypes and describes the generation of match probabilities using the haplotype analog of the formulae described in National Research Council (1996) Recommendation 4.2 which incorporates a theta (θ) correction (Section 10.3).  In Appendix 1 of these guidelines, SWGDAM provides estimations of theta (θ) using African American, Asian, Caucasian, Hispanic, and Native American population data from the U.S. Y-STR Database release 3.2 as well as references to other published estimates of theta (θ)  (Section 10.3.3) and acknowledges that the advent of new multiplexes (i.e., with additional-STR loci, or with a different set or subset of loci) may necessitate additional studies of theta (θ) as sufficient haplotype data becomes available for the new multiplex (Section 10.3.4).  The US Y-STR Database Release 4.2 (USYSTR Database) contains 2094 YFiler Plus haplotypes and has been tested by SWGDAM to estimate new theta (θ) values.  Based on its evaluation of these estimates, SWGDAM has chosen to re-evaluate these estimates should a larger sample size of YFiler Plus haplotypes be made available in a future release of the database.  SWGDAM continues to encourage laboratories to consider collaborating with the USYSTR Database to share their Y-STR haplotypes to augment the size of its datasets to increase both the genetic information and discrimination potential of this critical forensic resource.


Until YFiler Plus-specific θ estimates are available, USYSTR Database users who submit a 27-locus YFiler Plus haplotype can still obtain a count of the number of times the haplotype has been observed in the database, its relative frequency and the variation in this estimate based upon database size.  While the USYSTR Database does not presently calculate the theta-dependent match probability, due to the absence of estimates of theta (θ) values for this set of loci, should a YFiler Plus user wish to obtain a match probability estimate, he/she could re-submit the haplotype to the USYSTR Database omitting the YFiler Plus loci DYS449, DYS460, DYS518, DYS627, and DYF387S1. The resulting match probability would be conservative in that, necessarily, it doesn’t take into account the variation at the loci not submitted.


Partial Matching and Familial Searching


Q: There are different recommendations on your website for partial matching and familial searching.  Which is the most recent?                                                                                        


SWGDAM Response: Partial matches are different from familial searching.  A detailed description and explanation of the differences between partial matches and familial searching are available on the Federal Bureau of Investigation’s (FBI) CODIS website ( SWGDAM has reviewed issues relating to partial matches and familial searching and issued recommendations on each.  In 2009, SWGDAM issued recommendations that were developed in response to a specific request relating to the population genetics and statistics issues for partial matches that occur fortuitously during searches of the National DNA Index System (NDIS).  These recommendations were considered by the FBI in adoption of the plan for the release of information in the event of a partial match at NDIS (contained within the NDIS Operational Procedures Manual, Appendix G; available at  For laboratories considering the implementation of familial searching in their jurisdictions, a SWGDAM Ad Hoc Working Group provided guidance in 2013 on several specific questions posed by the FBI’s CODIS Unit  (see Recommendations from the SWGDAM Ad Hoc Working Group on Familial Searching; available at


National Commission on Forensic Science


QUESTION: What plans exist to transition SWGDAM from its current home in the FBI to the new Organization of Scientific Are Committees (OSAC)?

SWGDAM Response: Due to the unique statutory relationship between SWGDAM and the FBI with regard to the FBI Director’s Quality Assurance Standards (QAS) for DNA Laboratories, NIST and the FBI have agreed that SWGDAM will remain operationally with the FBI at this time.  The FBI also feels strongly that the business activities of the SWGDAM Committees are critical for the operation of CODIS and plans to continue managing the SWGDAM Committees to ensure not only that the QAS are revised in an efficient manner, but also that the National DNA Index System (NDIS) Procedures are timely and appropriate for the current or emerging technologies which are used by NDIS-participating laboratories nationwide.  Emerging forensic technologies such as Rapid-DNA testing and Next Generation Sequencing (NGS) are quickly becoming a reality, so the FBI must also ensure through SWGDAM that topics such as nomenclature and genetic privacy can be made fully compatible with the CODIS system.  Once the OSAC has disseminated guidance for the review and approval of standards and guidelines through its Forensic Science Code of Practice, draft SWGDAM guideline documents will be submitted for review and comment to the OSAC administration and all approved SWGDAM guidelines will be provided to the OSAC for inclusion in its Registry of Approved Standards or Guidelines, as appropriate.  Additionally, once the OSAC business structure has been formally memorialized, SWGDAM will review its current business process for drafting and approving guidelines which are captured in its Bylaws, and, to the extent possible, incorporate all elements of the review process designated for the OSACs.  This includes a public review period for all guidelines and proposed changes to the QAS which SWGDAM has now implemented and formally incorporated into its Bylaws.

SWGDAM Enhanced STR Detection Guidelines


QUESTION: The document contains a fallacy that low copy DNA is a method not an amount.  Low copy or low template refers to an amount of DNA.  That amount should be stated in this document and it is 100-200 pg, based on numerous scientific and internal validation studies.


SWGDAM Response: SWGDAM concurs that “low copy DNA” does literally refer to an amount of DNA recovered from a limited number of cells that yield a small number of allelic copies for a given genetic locus.  In our Guidelines for STR Enhanced Detection Methods, SWGDAM simply chose to employ the colloquial meaning of the term Low Copy Number Analysis as it is currently used by the forensic DNA testing community to indicate methods used for the purposes of increasing target signal for samples with low DNA template quantities.  These guidelines recognize that any conventional DNA typing method can be used on low levels of template DNA.   The document seeks to designate for special consideration those methods in which a standard method has been modified in such a way as to increase its overall sensitivity to the extent that stochastic phenomena must be taken into consideration.  SWGDAM felt that to strictly base its definition of low copy on a DNA mass (e.g., 100-200 pg) could have unintentionally oversimplified the several mechanisms by which a low copy sample can be obtained (e.g., degradation, inhibition, a minor contributor to a mixture, etc.).  In such samples, the DNA quantity can quantify safely in the non-low copy DNA range (e.g., 1 ng), but if an STR enhanced detection method is employed to overcome any low signal obtained using a conventional method, stochastic results can be detected.


QUESTION: The document [ignores] the issue of replicates.  The scientific literature is very clear.  Replicate analysis must be used when performing enhanced detection methods.


SWGDAM Response: Replicate testing is addressed in Section 4.1 of the SWGDAM Guidelines for STR Enhanced Detection Methods.  It is recommended for Low Template or Low Copy DNA Analysis which SWGDAM has cataloged as a special subset of enhanced detection methods.


SWGDAM Membership


QUESTION: How can I become a member of SWGDAM?


SWGDAM Response (Updated 08/2023): Sections II.C, II.D, and II.E of the SWGDAM Bylaws (approved September 2022) have been revised to update SWGDAM’s business process for appointing members, inviting guests, and engaging subject matter experts (SME).  Generally, SWGDAM receives nominations for participation from current SWGDAM participants or electronically via SWGDAM Contact Us and they are provided to the SWGDAM Vice Chair who chairs the SWGDAM Membership Committee.  The SWGDAM Vice Chair then contacts those individuals to gather their basic professional information via a straightforward application and the applicant’s CV.  The SWGDAM Membership Committee regularly reviews these applications and makes recommendations to the SWGDAM Chair as prescribed in the SWGDAM Bylaws.

SWGDAM Response: Section II.C of the SWGDAM Bylaws describes the formal business process for appointing SWGDAM members.  Currently, the SWGDAM Membership Committee receives nominations in the form of e-mail requests from the SWGDAM Chair that are either submitted directly to the Chair or through or another SWGDAM member/invited guest.  Each request must contain supporting professional information (such as a CV) for the individual requesting consideration for SWGDAM Membership.  Membership appointments are made on an as needed basis and are driven by the needs of SWGDAM as it carries out the responsibilities contained in its Bylaws.


SWGDAM Guidelines

QUESTION: SWGDAM recently published a “recommendation” [Recommendations of the SWGDAM ad Hoc Working Group on Genotyping Results Reported as Likelihood Rations].  Why wasn’t this [made] available for public comment before it was published?

SWGDAM Response (12/2018):  Section V.C.5 of the SWGDAM Bylaws states:

5. The committee will submit the final report to the Executive Board.  If the final report is a guidelines or standards document and the Executive Board approves the report for public comment, the Chair will, at a minimum, post the final report on the SWGDAM website for public comment for a minimum of 30 days.  Any comments received during the comment period will be submitted to the committee for consideration.

If a SWGDAM document is something other than a “guidelines or standards document” such as a SWGDAM recommendation, position statement, white paper, letter. etc., the SWGDAM leadership may determine that it is appropriate that the document be subjected to all, none, or only part of the review process prescribed in the SWGDAM Bylaws (Section V.C).  Additionally, in circumstances in which a change(es) made to a SWGDAM guideline document is/are deemed to be non-substantive by the SWGDAM leadership, such changes may or may not be subjected to all of the review elements of its bylaws.


QUESTION: I have noticed that in some commission reports, DNA presentations, and product descriptions statements are made that SWGDAM has reviewed or is aware of the content being discussed or that the content is in accordance with SWGDAM guidelines.  It is clear to me that most often this mention is made either to directly or indirectly suggest that SWGDAM endorses or agrees with the content or conclusions.  [What is the process for seeking SWGDAM endorsement or concurrence?]         

SWGDAM Response: SWGDAM’s mission as published in its bylaws is to provide guidance to the forensic DNA community on emerging issues and technologies as well as provide recommendations to the FBI Director for revisions to the Quality Assurance Standards.  To accomplish this mission, SWGDAM routinely solicits input from its members, invited guests, and others using a variety of methods to include presentations made at its regular meetings, dialogs made via, solicitation of public comments during the development of its guidance documents, and discussions at update sessions at professional meetings.  The sole purpose of these activities is to help better inform SWGDAM’s discussions and work product.  SWGDAM is neither positioned nor sanctioned to evaluate the merits of individual ideas, referee different procedural options, or to endorse products whether that idea, procedure, or product is presented by a SWGDAM participant or other individual.  While SWGDAM has been made aware of situations like the ones cited [not listed here], it does not routinely respond directly to such notifications nor does it investigate incidents or pursue clarifications in the source materials.


QUESTION: I am reading a SWGDAM standard and am in need of some clarification. The details of my question are below and I would appreciate a response.                                                                                          


SWGDAM Response: Neither SWGDAM nor its individual members or invited guests are able to referee individual interpretations or applications of specific elements of any of its guideline documents.  While individual scientists may feel the guidance for any one element unclear or incomplete, SWGDAM has made its best attempt to express the general intent of each element as clearly as possible.  Like all such inquiries, this comment will be discussed internally by SWGDAM to determine if it may be of value to revise a guidelines immediately, develop a general response as an FAQ to share with the forensic DNA community as a whole, or retain it for consideration during its next revision cycle for a document.  As with all such operational inquires, SWGDAM recommends that forensic DNA professionals discuss the content of any applicable SWGDAM document with their peers across the forensic DNA testing community to help inform their individual decision making.

QUESTION: Since the various SWGDAM Guideline documents are more detailed than the FBI QA Standards, why aren't labs held accountable to the specifics within each of the Guideline documents?                                                               

SWGDAM Response: The FBI Director’s Quality Assurance Standards for Forensic DNA Testing Laboratories and the Quality Assurance Standards for DNA Databasing Laboratories (referred to hereafter collectively as the QAS) are the minimum quality assurance requirements to ensure that a laboratory will generate quality results and are required by law for forensic laboratories that participate in the National DNA Index System (NDIS). The standards cover all areas such as the education and experience of personnel working in the laboratory, the validation of analyses and processes used by the laboratory, equipment, proficiency tests, reports, audits and health and safety.  SWGDAM’s principal responsibility is the recommendation of revisions, as required, to these minimum quality assurance standards.

SWGDAM also periodically issues new and revises existing guideline documents intended to provide additional best-practice recommendations to the forensic DNA community, consistent with the minimum standards, on relevant new techniques or topics of interest to the DNA community such as data interpretation, validation, and training. SWGDAM will often incorporate elements previously included in a new or revised SWGDAM guideline into its proposed revisions to the QAS for the purposes of elevating that previously identified best-practice to a new minimum standard required for participation in NDIS.  If incorporated as a minimum standard for a quality assurance program, this requirement will be subject to the QAS audit process. As a result, while SWGDAM guidelines may contain a greater level of specificity, be broader in scope, and represent SWGDAM’s recommendations for industry best practices that conform to all existing minimum QAS requirements, it is only the QAS that contain the minimum quality assurance standards for participation in NDIS as assured through the formal auditing process.  It should also be noted that the requirements of the QAS are most often adopted by accrediting bodies and incorporated into their individual assessment criteria for forensic DNA testing laboratories and enforced via the accreditation inspection process.


QUESTION: Has SWGDAM published a set of verbal equivalents for describing likelihood ratios?            


SWGDAM Response: While SWGDAM continues to discuss the reporting of likelihood ratios, it has not published guidance for the use of verbal equivalents or scale of conclusions.  In an effort to assist you in this matter, SWGDAM is aware that at least 2 groups have published information on this topic:  the Association of Forensic Science Providers in Science and Justice 49 (2009) 161-164 and the European Network of Forensic Science Institutes (ENFSI) via its ENFSI Guideline for Evaluative Reporting in Forensic Science entitled Strengthening the Evaluation of Forensic Results across Europe (STEOFRAE) .  Please understand that SWGDAM did not participate in the development of either of these sources nor is it in a position to endorse either document.  SWGDAM is simply providing these potential 2 sources here as points for those interested to continue their search for potential guidance on the existence and use of LR verbal equivalents.


SWGDAM Response (Updated 08/2018):  SWGDAM has issued Recommendations of the SWGDAM Ad Hoc Working Group on Genotype Results Reported as Likelihood Ratios which is available on the SWGDAM Publications Page.



QUESTION: I was wondering if [SWGDAM] will be posting public comments on the SWGDAM Validation Guidelines for Probabilistic Genotyping software?  I am interested in seeing what the forensic community had to say about them.


SWGDAM Response: SWGDAM's Bylaws (V.C.5) do not currently specify that SWGDAM make the public comments it receives available for review upon the completion of the public comment period. In formulating its business model regarding soliciting public comments on its proposed changes to the Quality Assurance Standards (QAS) and its guidance documents, SWGDAM preformed a business analysis on the other 19 Scientific Working Groups (SWGs) in existence at the time and adopted a hybrid model based on the different strategies identified across the spectrum of SWGs.  Currently, SWGDAM solicits public comments, acknowledges their receipt, and forwards them to the committee or working group of interest for consideration.   On occasion, SWGDAM will place a specific comment it receives during the public comment period, together with SWGDAM's response, on the FAQ Page of if it believes that a comment may be of special interest to the forensic DNA community.


QUESTION: What are guidelines and how should they be used?


SWGDAM Response: Guidelines recommended by SWGDAM are intended to provide additional guidance to the DNA community on current relevant topics.  These guidance documents are simply that and should not be viewed or treated as requirements or minimum standards for forensic DNA laboratories.  SWGDAM will update guidelines as needed to ensure that such guidance is in accord with the available scientific information and best practices at that time. 


QUESTION: Within many of the SWGDAM guidelines the statement is made that these guidelines are not intended to be used retroactively. What is the intent of this “retroactive” statement?


SWGDAM Response:  SWGDAM includes a “retroactive” statement with the intent that the revised guidance be applied prospectively and not retroactively.  With the underlying assumption that work (validation, training, analysis, interpretation) performed prior to the issuance of the revisions was appropriate and scientifically valid, revision of the applicable guidelines is not intended to invalidate or call into question the previous work.


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SWGDAM STR Interpretation Guidelines


QUESTION: I'm reading SWGDAM standard 4B.12 and am in need of some clarification. It states:

4B.12 If the laboratory does not have the capability to perform an LR using all the available information (e.g., the possibility of undetected data or alleles that are indistinguishable from stutter) and the POI is interpreted as being included at the locus, then the LR for the locus may be assigned a neutral value of 1/1. It would be inappropriate to assign this neutral value for a POI whose genotype is interpreted as being excluded at the locus. Instead, the POI should have been excluded as part of the interpretation.

In applying the above guideline, if a person is determined to be included in the overall profile (and hence not excluded by any particular locus), is it proper to input a value of 1 at a locus where that individual’s alleles are not completely and fully represented in the data?  Or should this constitute exclusion for the individual at that particular locus since they are not fully represented


SWGDAM Response: The assignment of a neutral LR (1/1) should only be applied when the POI is interpreted to be included in the overall profile, and the lab does not have the statistical tool available to properly include all possible genotypes that should be included in the denominator (e.g., genotypes that include possible missing alleles or alleles that are indistinguishable from stutter).  The genotype of the POI should not matter when interpreting all possible genotypes that should be included in the denominator; this interpretation should have been made prior to bringing in the POI for comparison.










Evidence is intimate to the victim and interpreted as a two contributor mixture.  Evidence is allele 9 (1000 RFU) and allele 10 (1000 RFU) and allele 12 (100 RFU), Victim is genotype 9,10.  Overall ratio of contributors is ~ 10:1 with the victim being the major contributor.  With the allele 12 being below the stochastic threshold (ST), it is possible that the second contributor to the evidence may have an undetected allele (e.g., be genotype 12,13 or 12,14).  The interpretation for the minor contributor is that they must have the allele 12 in their genotype, and the second allele may be any other allele (either masked by the Victim, a homozygous genotype, or an undetected second allele).  If the POI has an allele 12 in their genotype, they are not excluded (even if their second allele is not represented in the evidence).  If the lab does not have a statistical tool to apply a "2P" calculation in the denominator (to account for all genotypes that include allele 12 and any other second allele), they may apply a LR value of 1 to this locus.  The interpretation is that the POI is not excluded (the POI has the requisite allele 12 in their genotype), but the lab cannot properly calculate a LR that includes all appropriate genotypes for the denominator of the LR. 
However, if the allele 12 was above the stochastic threshold then the laboratory interpretation for the minor contributor should only be genotype 9,12 or 10,12 or 12,12.  In this instance, if the POI’s genotype was 12,14 then they should be excluded as a contributor at this locus as part of the interpretation.  Assigning a neutral value of 1/1 would not be appropriate.  


QUESTION:  I have heard that SWGDAM has done webinars on the 2017 STR guidelines.  Where are they?


SWGDAM Response:  SWGDAM has collaborated with the American Society of Crime Laboratory Directors (ASCLD) to provide webinars on topics related to its 2017 SWGDAM Interpretation Guidelines for Autosomal STR Typing by Forensic DNA Testing Laboratories.  They include:

ASCLD DNA Mixtures Webinar: Technical Overview - Archival

This webinar was targeted to DNA Technical Leaders, Quality Managers, DNA Supervisors and DNA Analysts. There was a question and answer period after the presentations.

ASCLD Webinar: DNA Standards and Guidelines - Archival

This webinar was targeted to DNA Supervisors, DNA Technical Leaders, Quality Mangers, and DNA Analysts.  There was a question and answer period after the presentation.


Please visit for the archival links to these events.


SWGDAM Review/Endorsement/Comment


QUESTION: I would like your [SWGDAM’s] opinion on expert testimony in STR DNA analysis for a CODIS/ASCLD accredited laboratory.  Would it be appropriate for a laboratory administrator to provide expert testimony in STR DNA analysis/reports/statistics if they have never been qualified, trained, competency or proficiency tested in STR DNA analysis?  What is the recommended policy if the original scientist is not available to testify to their DNA report?


SWGDAM Response: SWGDAM’s mission as published in its bylaws is to provide guidance to the forensic DNA community on emerging issues and technologies as well as provide recommendations to the FBI Director for revisions to the Quality Assurance Standards.  As a result, SWGDAM is neither sanctioned nor positioned to have sufficient familiarity with individual legal requirements to provide opinions on specific situations or cases. As rules vary by jurisdiction, an organization’s legal counsel or local prosecutor would be in the position to advise you in this matter.


QUESTION: I write and edit for [a website] and we’re working on a new article that will pull together the best online information sources on forensic DNA analysis.  I think my readers would be very interested in [SWGDAM’s] site.  Would it be alright for me to reference it in my article with a brief description?  I would also like to request [SWGDAM’s] recommendations for other useful websites covering forensic DNA analysis.  If you have any suggestions for additional sites that I could reference in this article, would you let me know?


SWGDAM Response: Thank you for your interest in the SWGDAM website.  SWGDAM is primarily a research working group that provides guidance documents for the forensic DNA community and, as such, is not in a position to endorse any article, publication, website, etc.  Permission is not needed, however, to include the SWGDAM website ( as a reference for informational or resource purposes.


QUESTION: I have attached a document to be forwarded to SWGDAM members for comments. This document has been drafted [as] one of a series of minimum requirements. This document is not the duplication of existing standards and is not intended to replace existing guidelines. Please send me SWGDAM's comments by so they can be incorporated into the final document.                     


SWGDAM Response: Under our Bylaws, SWGDAM’s primary mission is to recommend minimum quality standards for the FBI Director that are applicable to forensic DNA laboratories in the United States that participate in the National DNA Index System. Compliance with the FBI Director’s Quality Assurance Standards is required by Federal law.  While we appreciate to whom your document is intended to apply but because it is a standards/requirements document, SWGDAM cannot participate in or endorse the document.

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 SWGDAM mtDNA Database


QUESTION: The link provided by much of the scientific literature to the SWGDAM mtDNA database seems to be broken.  Has this page simply been moved?                                                                        


SWGDAM Response: The following link will work to obtain the same reference:

The above link is to an article published in 2002 on the public mtDNA population database through which the public version of the database could be downloaded.  This link was provided in the now superseded April 2003, SWGDAM Guidelines for Mitochondrial DNA (mtDNA) Nucleotide Sequence Interpretation.  Please note that the database was written in software that is not compatible with some Windows-based operating systems.  In general, the newer the Windows-based operating system, the less likely the old database program is to work.  Additionally, the public mitochondrial database is no longer supported by the FBI.  Practitioners are encouraged to consult the July 2013, SWGDAM Interpretation Guidelines for Mitochondrial DNA Analysis by Forensic DNA Testing Laboratories  for SWGDAM’s current recommendations for population frequency estimates for a given mtDNA haplotype.


Rapid-DNA Technology


QUESTION: For the following question, assume that developmental validation of the R-DNA instrument has been completed and that an NDIS Participating Laboratory has internally validated the R-DNA instrument according to its standard operating procedures.  Although the R-DNA instrument has not been approved for use at NDIS, can the DNA records from this instrument be stored and searched at SDIS?   


SWGDAM Response:  Because the R-DNA instrument has not been approved for use at NDIS, the DNA records would not be eligible for upload to NDIS.  For entry in SDIS, it will be up to each individual state to determine if these DNA records will be eligible for upload to SDIS since the records are generated by an R-DNA instrument that has not been approved for use at NDIS (this could mean that the typing amplification test kit and/or expert system are not approved for use at NDIS).  If a state determines that these DNA records are eligible for upload to SDIS, prior to such upload, the DNA records must be interpreted and technically reviewed in accordance with the requirements of QAS Standards 9.6 and 12.2. 


QUESTION: Does laboratory accreditation extend outside the laboratory facility? For example, if a R-DNA instrument is internally validated in the laboratory facility, would the laboratory’s accreditation be applicable to the use of the R-DNA instrument in a mobile crime scene processing vehicle?     


SWGDAM Response:  This question is beyond SWGDAM’s scope as it is involves laboratory accreditation.  You will want to direct this inquiry to the NDIS approved accrediting agencies, the American Society of Crime Laboratories/Laboratory Accreditation Board ( and/or Forensic Quality Services/ANSI-ASQ National Accreditation Board (


QUESTION: Standard 9.4 of the Quality Assurance Standards for Forensic DNA Testing Laboratories effective 9-1-2011 states, “The laboratory shall quantify the amount of human DNA in forensic samples prior to nuclear DNA amplification. Quantitation of human DNA is not required for casework reference samples if the laboratory has a validated system that has been demonstrated to reproducibly and reliably yield successful DNA amplification and typing without prior quantitation.”  Please verify that quantitation is not required from a rapid DNA analysis instrument that has not yet been approved by NDIS for casework reference samples if the laboratory has a validated system that has been demonstrated to reproducibly and reliably yield successful DNA amplification and typing without prior quantitation.              


SWGDAM Response:  That is correct.


QUESTION:  To follow-up, would it be possible for data from a R-DNA instrument that does not quantitate the sample and that has not yet been approved by NDIS for forensic, casework samples [casework forensic samples] to store the data in an Index that does not get promoted to a higher level and use this data to search against all the existing stored data from the casework sample at LDIS and/or SDIS?                                               


SWGDAM Response: No, the analysis of forensic casework samples by an R-DNA instrument would not be compliant with the FBI Director’s Quality Assurance Standards for Forensic DNA Testing Laboratories (QAS; for example, QAS Standards 9.4 and 12.2).  SWGDAM is not currently considering or discussing the application of the QAS to the analysis of forensic casework samples by a R-DNA instrument.


QUESTION: Can profiles generated from unknown samples that have not been quantified be entered into a lab’s LDIS if it can be assured not to be promoted to SDIS and/or NDIS?  If not, can you reference the source that states that either of these procedures is prohibited?                                                      


SWGDAM Response: No, the DNA records that you describe would not be in compliance with the FBI Director’s Quality Assurance Standards for Forensic DNA Testing Laboratories (QAS).  While the upload and storage of DNA records at LDIS is not addressed in the QAS, the NDIS Operational Procedures Manual (NDIS Manual) prohibits the storage of such DNA records at LDIS.  Specifically, Section 3.4 of the NDIS Manual provides that “[t]he NDIS participating laboratory is responsible for maintaining a system of controls to ensure that DNA records are maintained and used in the Local DNA Index System (LDIS), the State DNA Index System (SDIS) and NDIS in accordance with the Federal DNA Act and applicable State law, and for NDIS, in accordance with the NDIS Privacy Act Notice” [emphasis added] available at


QUESTION: When will Rapid DNA system developmental validation guidelines be provided?


SWGDAM Response: Developmental validation of the Rapid DNA instruments should be conducted in accordance with the requirements of the FBI’s Quality Assurance Standards for DNA Databasing Laboratories (QAS), specifically Standard 8.2 (available at  Additional guidance on developmental validation is provided in the SWGDAM Validation Guidelines for DNA Analysis Methods available at


If an NDIS approved typing amplification kit is used, without modification to the loci, by the Rapid DNA instrument, then the characterization of genetic markers and population studies may not be necessary for the developmental validation, as further explained in the SWGDAM Letter to R-DNA Developers available at  Additionally, if the Rapid DNA instrument uses an Expert System, then an NDIS Participating Laboratory must submit such Expert System for approval in accordance with Chapter 4 of the NDIS Operational Procedures Manual available at


QUESTION: When will Rapid DNA system internal validation guidelines be provided for accredited laboratories?


SWGDAM Response:  Similar to developmental validation, internal validation of the Rapid DNA instruments should be conducted in accordance with the requirements of the FBI’s QAS, specifically Standard 8.3 (  Additional guidance on internal validation is contained in the SWGDAM Validation Guidelines for DNA Analysis Methods (


QUESTION: Please provide some clarity on the process and timeline to obtain developmental validation guidelines.


SWGDAM Response:  As noted in the previous responses to inquiries concerning Rapid DNA instrument validation, please refer to Standards 8.2 and 8.3 of the FBI’s QAS provide the requirements for developmental and internal validation, respectively (  The SWGDAM Validation Guidelines for DNA Analysis Methods include additional guidance on validation (


QUESTION: How will each company be involved in the development of the guidelines?


SWGDAM Response:  Developers of the Rapid DNA instruments will be responsible for conducting the developmental validation of their respective instruments in accordance with the FBI’s QAS.


QUESTION: Success is defined as ???


SWGDAM Response:  According to the objectives of the FBI’s Rapid DNA initiative, success is considered the generation of an accurate 13 CODIS core STR loci profile for the DNA sample input into the Rapid DNA instrument.  The CODIS and NDIS Fact Sheet provides additional information on the Rapid DNA initiative and is available at


QUESTION: Please discuss controls and how often they might need to be run.


SWGDAM Response: QAS Standard 9.5 defines the required controls for known DNA samples (  Until the validation studies are completed by the Rapid DNA Developers and the studies/data reviewed, Rapid DNA instruments must comply with the currently defined QAS controls. 


If the validation studies/data produced by the Rapid DNA Developers demonstrates that the existing QAS controls may not be appropriate for the Rapid DNA instruments, or if additional/new controls are warranted for Rapid DNA instruments, revisions to the QAS will be considered at that time. 


QUESTION: What type of reports from the Rapid DNA system would enable quality assurance for auditors?


SWGDAM Response: The validation studies/data on the Rapid DNA instruments will indicate what type of reports are appropriate for monitoring quality assurance.  Subject to such studies/data, examples of reports currently used to monitor quality assurance, include, but are not limited to, the following: audit trail reports; system performance reports; and expert system’s rule firing reports.


QUESTION: Would adoption of a Rapid DNA system be simplified if use of the expert system is optional?


SWGDAM Response:  At the current time, submission of a Rapid DNA instrument for use at NDIS would require the following:


If the Rapid DNA instrument has successfully completed the required validations, is QAS compliant, and the typing amplification test kit has been approved in accordance with paragraphs 1-4 above and an NDIS laboratory implements such Rapid DNA instrument prior to the approval of its Expert System, the NDIS laboratory using that Rapid DNA instrument is responsible for performing the review required by QAS Standard 12.2.2 before a sample is eligible to be uploaded to NDIS.


QUESTION: We received the communication on 2/15/13 [a reference to the SWGDAM Open Letter to R-DNA developers dated February 15, 2012] and much of it pertained to 'Expert System'. I have reviewed the literature, but I want to be sure that I have the correct references for the approved Expert Systems submitted by the NDIS Participating Laboratories. At your convenience, can you please forward me the citations for the approved Expert Systems (GeneMapper(r)ID,GeneMapper(r)ID-X,i-Cubed(tm), TrueAllele(tm)).


SWGDAM Response: Information on approved Expert Systems and NDIS approved PCR kits will be updated regularly on the CODIS and NDIS Fact Sheet so that is the best reference for the most current information. The CODIS and NDIS Fact Sheet is available at

The information will also be contained in the NDIS Operational Procedures Manual but plans are to update the manual annually.


QUESTION: I had also expected that there might [be] rDNA specific guidelines that the rDNA committee are drafting. Is this still the plan and if so is there a timeline for a draft version?


SWGDAM Response: Please reference the SWGDAM Open Letter to R-DNA Developers dated February 15, 2012 that describes the importance of documented developmental validation studies and detailed descriptions of deployed expert system(s) before SWGDAM can have the substantive discussions necessary to amend any relevant existing guideline(s) or create a guidance document specific to Rapid-DNA technologies. As in the past for other new technologies, SWGDAM expects that the first such amended or new guidelines would provide guidance to forensic DNA laboratories for the internal validation or R-DNA technologies for use within the laboratory setting.


Vendor Presentations


QUESTION: I wanted to see if it would be possible to get on the agenda for SWGDAM’s next meeting. We would like to address two topics: first our enhancements to product quality standards, and second the development of our STR kits. We know the topic of DNA free products and enhancement of product specifications has been a topic for the DNA forensic community. We would greatly appreciate the opportunity to speak on the topics at your next SWGDAM meeting.


SWGDAM Response: Thank you for your interest in speaking to SWGDAM. As in the past, should SWGDAM organize a vendor-based session on either of the topics you mention, I will contact you as well as any other vendor(s)that may have information of interest to our membership.


Serology Guidelines

QUESTION:  A few scientists have stated that new SWGDAM guidelines prohibit stating semen is present regardless of the levels [while others disagree with that] conclusion.  Would SWGDAM consider allowing elevated levels of PSA detected be a confirmation for the presence of seminal fluid?  In the case of PSA, could a lab, after running validation and research, choose to set a threshold as a positive result for seminal fluid?  I've also noted that during your meetings, you have had several workshops.  Would you consider allowing me an opportunity to demonstrate the detection of PSA by immunochromatographic membranes[?]  I realize that your group can not endorse or recommend a manufacturer's product.

SWGDAM Response:  As with all SWGDAM guideline documents, the Guidelines for the Collection and Serological Examination of Biological Evidence are intended to provide consensus-based best practice direction for the forensic biology community and should not be viewed or treated as requirements or standards for laboratories conducting forensic serological and/or DNA testing.  Should a laboratory decide to implement any new serological test, Section 8:  Validation/Method Introduction and Section 10:  Analytical Procedures of these guidelines provide recommendations for procedures to 1) evaluate a method’s efficacy and reliability and 2) properly implement it for forensic casework analysis. It is the accumulation of this test data within the laboratory which establishes that a method performs as expected.  The internal validation studies conducted by the forensic laboratory should be sufficient to support and document the reliability of the technology as practiced by that laboratory.  These studies should also be the basis of the laboratory’s standard operating procedures for any new analytical method to ensure operational uniformity and to minimize analytical drift.  Please refer to the Vendor Presentation section of this FAQ for information regarding that portion of this inquiry concerning the opportunity to address SWGDAM at one of its regular meetings.


QUESTION: Our lab is looking for a ‘governing body’ for Serology.  Our Serology Section has been searching for guidelines that compare to SWGDAM guidelines.  They have been unable to locate any.  Are there any guidelines or plans to have any that relate specifically to Serology.  If there are guidelines for Serology will you please direct me to the updated version.


SWGDAM Response: SWGDAM has not issued any guidance documents related to serological testing.  It has had committees over the years discuss this area and prepare draft documents, but the body proper has never formalized and approved a work product specific to serological testing.  Given the group’s current list of outstanding taskings, SWGDAM has no plans for convening another such working group in the near future.  Ultimately, any future convening of a serology committee by SWGDAM will depend on the perceived need for such guidance and the determination that serological testing falls within the scope of SWGDAM and not another extant or future guidance group.


SWGDAM Response (Updated 09/2013):  The QA Committee of SWGDAM is currently developing guidelines for the performance of forensic serological testing.


SWGDAM Response (Updated 01/2015):  SWGDAM has issued Guidelines for the Collection and Serological Examination of Biological Evidence.


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Miscellaneous Topics

QUESTION: What type of validation data are needed to establish a contamination tolerance level?       


SWGDAM Response: During the validation of a new procedure, multiple negative controls and reagent blanks, as appropriate, should be processed alongside the samples in order to sufficiently assess the risk of contamination.  If any blank control yields a positive result, determine if the positive result is interfering with the accurate typing of associated samples. Using the positive results from all blank controls collectively, a laboratory has the option to define a tolerance level by which sample data are still reportable.

If blank controls do not yield any positive results during the validation, a laboratory can still define what would be considered gross contamination based on general guidelines. Some examples of a contamination tolerance level in which sample data may be considered reportable are:

  1. If detectable profile/sequence data are below analytical threshold.

  2. If the profile/sequence data are extremely limited, i.e., one peak above the analytical threshold.

  3. If the profile/sequence data are not consistent with the sample data.


QUESTION: Is there a [SWGDAM] newsletter to keep [interested parties] up to date about possible new versions of [SWGDAM] guidelines?


SWGDAM Response: SWGDAM does not issue a newsletter.  At this time, SWGDAM does not have the infrastructure or resources to generate a physical or electronic door-to-door vehicle for distribution to interested parties. Rather SWGDAM has focused its communication efforts on the development of its website which is hosted by the National Institute Standards and Technology (NIST).  Currently, SWGDAM uses its website to provide its guideline documents and other work product to interested parties and for notifications to the forensic DNA community via the News and Information section of its Home Page.  SWGDAM has found this website to be the most efficient vehicle for it to provide real-time updates to interested parties on SWGDAM’s activities such as the issuance of guidelines.  SWGDAM does attempt to provide updates on it activities at professional meetings as often as practicable, but given the recent intermittent nature of such updates due to funding limitations, continues to be the best portal for timely information on our activities.


QUESTION: I [work] for a smaller agency whose only in-house work is fingerprint examination. However, we are also responsible for the collection of DNA at various types of scenes, and for training Deputies on DNA collection at minor property crime scenes. My question is - does SWGDAM have a stance on proper collection of possible Touch/Contact DNA, and if so then what are your recommendations? I have heard conflicting opinions from DNA analysts at various laboratories.


SWGDAM Response:  SWGDAM has developed no guidance for the collection of samples to be subjected to either conventional DNA testing or enhanced detection method (EDM) testing.   With respect to the conflicting opinions across DNA analysts you cite, SWGDAM acknowledges that multiple viable approaches do exist for the removal/collection of biological material from items of evidence and supports practitioners utilizing those sample collection methods that work best for them for the recovery of DNA for forensic testing.


QUESTION: I am a researcher and am wondering how many samples total does the SWGDAM database have, and/or where can I retrieve this information?


SWGDAM Response:  SWGDAM does not maintain a database of samples and/or DNA typing information of any kind.  If you are referring to the National DNA Index System or NDIS  containing the DNA profiles contributed by federal, state, and local participating forensic laboratories, information on the statistics for the national level and state contributions is available at  FBI — Combined DNA Index System under NDIS Statistics.


QUESTION: What are the retention policies and procedures of DNA for SWGDAM?  If the answer is lengthy, you may just point me in the right direction.


SWGDAM Response:  To date, SWGDAM has not issued a guidance document regarding DNA retention policies and procedures. Resources that may serve as a starting point for this inquiry include: Technical Working Group on Biological Evidence Preservation, The Biological Evidence Preservation Handbook, and What Every Law Enforcement Officer Should Know About DNA.


QUESTION: Does SWGDAM have a newsletter?


SWGDAM Response: SWGDAM does not currently produce a newsletter.  Since 2014, SWGDAM has used its website as its primary vehicle for engaging with the forensic DNA community and providing updates to interested parties on its work such as the issuance of new or revised guidelines.  This website is a collaboration between SWGDAM and the National Institute of Standards and Technology (NIST) and it is updated regularly with information regarding SWGDAM’s meetings and committee activities.  While SWGDAM also attempts to provide updates on it activities at meetings of the various professional and scientific groups associated with forensic DNA testing, continues to be the best resource for timely information on our activities. 


Product Inquiries


QUESTION: My company is interested to learn more about the procedures required to obtain SWGDAM review of a technology.  We have invented and are selling worldwide a product that is widely used but that has not been formally reviewed for forensic use.


SWGDAM Response: SWGDAM does not conduct product validations. Rather, the group publishes guidelines for forensic DNA laboratories to follow for the implementation of new procedures.  Verification that a laboratory has properly evaluated a new method prior to its implementation is accomplished via the audit process that is a required of all Combined DNA Index System (CODIS) participating DNA laboratories.  Whether the existing guidelines provide sufficient guidance for the thorough evaluation of a given product is ultimately the decision of the laboratory performing the evaluation which can chose to do additional testing (the adequacy of which is ultimately confirmed or refuted by the audit process).  Should you wish to evaluate your product using experiments recommended by SWGDAM, please conduct those tests recommended in SWGDAM’s Guidelines for the Validation of DNA Analysis Methods that you believe could empirically demonstrate the advertised performance of your product or you could contact, and potentially partner with, a CODIS participating laboratory to conduct these evaluations.  These experiments could serve as your product’s developmental validation that any forensic DNA laboratory interested in evaluating the product could then cite as a part of its internal validation process.


QUESTION: My company believes that robotics and software validation are needed in the community and that there is little in the Quality Assurance Standards (QAS) on these areas. I would like to organize a discussion with SWGDAM to clearly define the requirements for software and robotic validations and performance checks to ensure we serve the needs of each laboratory (whether they perform their own internal studies or we provide the service).


SWGDAM Response: Thank you for your interest in speaking to SWGDAM.  Generally, SWGDAM receives suggestions from the forensic DNA testing community for new guidance documents, revisions to existing documents, or suggestions for changes to the FBI’s Quality Assurance Standards for Forensic  DNA Testing Laboratories and Quality Assurance Standards for DNA Databasing Laboratories through its membership, public meetings, or  To date, SWGDAM has receive no requests from the forensic DNA community to suggest additional guidance be added to Standard 8 of the FBI’s Quality Assurance Standards for the validation of software or automated platforms.  Likewise, SWGDAM has received no feedback from the forensic DNA community that the current audit process (that utilizes these standards) is not adequate for evaluating the various approaches that laboratories currently use for the validation of software and automated DNA processing platforms.  However, based on general feedback from the forensic DNA community regarding the Quality Assurance Standards, SWGDAM is currently in the process of developing a new guidance document that contains examples of issues that have arisen as a part of the auditing process and the guidance or interpretation of the requirement or source that was applied in that specific occurrence.  It is hoped that this ”examples” document, being developed by SWGDAM’s Quality Assurance Committee, will provide contextual information regarding the application of the various standards and thus better enable the forensic DNA community to understand the intend of the requirement or source.  This document may be another viable mechanism for identifying any future need for additional guidance in the areas of software and automation validation as well as providing a more real-time vehicle to provide additional useful guidance to DNA testing laboratories.  Should SWGDAM become aware of a more systemic need for guidance in the rapidly changing areas you mention and decide that a vendor-based session is warranted, I will contact you as well as any other vendor(s) that may have information of interest to our membership.


Quality Assurance Standards (QAS) Inquiries

QUESTION: I need to review the QAS in place for public labs conducting CODIS database searches in 2006. Would you be able to send me a copy of the 2006 QAS that public labs would rely upon when doing their internal or external audits? If there is a publication from that year that includes annotations, explanations of best practices, etc…


SWGDAM Response:  (Published 8/19/20) Proposed revisions for the FBI DNA Quality Assurance Standards (QAS) have been approved by SWGDAM in 2007, 2008, 2011, and 2020 and forwarded to the FBI Director for his consideration. The FBI Director approved the current QAS and issued them with an effective date of July 1, 2020 and they are available at the FBI’s web site at The QAS in effect in 2006 would have been the following: 1) Quality Assurance Standards for Convicted Offender DNA Databasing Laboratories (April 1, 1999 - June 30, 2009) available at and 2) Quality Assurance Standards for Forensic DNA Testing Laboratories (October 1, 1998 - June 30, 2009) available at Both of these QAS documents were originally published in the July 2000 issue of the FBI’s Forensic Science Communications

QUESTION:  Our laboratory uses a technician to conduct Y-screening.  Results are turned over to the analyst, and the analyst determines which samples to take forward for extraction through typing.  Does the technician need to be proficiency tested for Y-screening?


SWGDAM Response:  Yes.  Extraction and quantification are both DNA methodologies, even if used for screening purposes, covered under the FBI Quality Assurance Standards.  Proficiency testing can be accomplished by allowing the technician to conduct Y-screening on the same proficiency test assigned to the analyst who performs the extraction through typing methodologies.  While the Y-screening results may not be reported to the proficiency test provider, the results are documented and could be tracked internally based on the laboratory’s reporting strategy. SWGDAM has also issued a Clarification on Proficiency Testing of qPCR Workflows Including Y-screening which is available on the SWGDAM Publications Page.



QUESTION: Under what circumstances can Probabilistic Genotyping be performed on electronic data, including platforms and kits used prior to a lab's current methods?


SWGDAM Response: Provided that the following 2 conditions are met, probabilistic genotyping can be performed on any electronic data:
1.  The electronic casework data to be analyzed using the probabilistic genotyping system of choice was generated in compliance with all applicable requirements of the FBI National Quality Assurance Standards (QAS), and

2.  The validation of the probabilistic genotyping software to be used also included the analysis of data generated by the historical platform and kit and the validation as a whole was conducted in compliance with all applicable requirements of the QAS.


QUESTION: Further to the discussion on Standard 13 of the QAS and evaluation of comparisons between two different chemistries, does a difference in the use of stutter position peak data between the original statistical method (e.g. CPI and a stutter peak, or peaks, not used as an allele in the calculation) and a different statistical method (e.g. Likelihood Ratio or probabilistic genotyping LR and a stutter peak or peaks used as an allele in the calculation)  constitute a re-interpretation of the old data and, therefore, require competency/proficiency testing?  


SWGDAM Response:  SWGDAM has received a number of inquiries regarding the evaluation of historical data in the context of new comparisons.  SWGDAM has formed a Committee of Detail that will begin meeting at the January 2016 Regular SWGDAM Meeting and advise our standing QA Committee on the following taskings: 

1.  Propose recommendations to the QA Committee in the form of additions to SWGDAM’s QAS Clarification Document to provide guidance on how NDIS participating laboratories must operate to appropriately handle comparisons of new data to historical data in accordance with the current QAS (whether they chose to reinterpret that data or simply use the historical data for comparison purposes).
2.  Propose recommendations to the QA Committee in the form of changes to the current QAS to further clarify what constitutes reinterpretation of historical data and the changes necessary for further ensuring that all such reinterpretations and/or comparisons of historical data to new data are performed appropriately and reproducibly by competent scientists within NDIS participating laboratories.


SWGDAM Response (Updated 07/2016):  SWGDAM has issued a SWGDAM Clarification on the Reinterpretation of Data Typed with Legacy Amplification Test Kits and continues to respond to selected inquires under the Reinterpretation of Legacy Amplification Kit Data header on the SWGDAM FAQ Page.


QUESTION: Standard 5.5 of the QAS for forensic labs refers to technical reviewer, is this only in reference to individuals employed solely to review or does this refer to DNA analyst who perform technical review as part of their job duties. This leads to the question if an analyst works cases including technical review does this person need to technically review an external proficiency test twice a year? This question arose as part of an internal audit.

SWGDAM Response:  While SWGDAM does recommend revisions, as needed, to the FBI Director for the Quality Assurance Standards for Forensic DNA Testing Laboratories and the Quality Assurance Standards for DNA Databasing Laboratories, all questions regarding the QAS auditing process or the findings of a specific audit should be directed to the Combined DNA Index System Unit of the FBI Laboratory at or 703-632-8315.  More information may be obtained at FBI — Combined 
DNA Index System.


SWGDAM Response (Updated 02/2016):  The QAS define a technical reviewer as “an employee or contract employee who is a current or previously qualified analyst in the methodology being reviewed that performs a technical review of, and is not an author of, the applicable report or its contents.”   The Audit Document states that a technical reviewer “must also participate in an NDIS laboratory’s external proficiency-testing program to the full extent in which he or she participates in the review of the DNA data.  The intent is that any contract employee hired to conduct technical reviews participates in an external proficiency testing program administered by an NDIS participating laboratory for the technology, platform and amplification test kit used to generate the data being reviewed and that the term of the employment does not impact or negate the requirement to participate in such external proficiency testing.”  An analyst who performs technical reviews as a task incidental to his/her analyst duties is not required to technically review an external proficiency test twice a year.


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