OSAC 2020‐N‐0007

Best Practice Recommendations

for the Management and Use of

Quality Assurance DNA Elimination

Databases in Forensic DNA

Analysis

Human Forensic Biology Subcommittee

Biology Scientific Area Committee (SAC)

Organization of Scientific Area Committees (OSAC) for Forensic Science
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OSAC Proposed Standard

OSAC 2020‐N‐0007

Best Practice Recommendations for the

Management and Use of Quality

Assurance DNA Elimination Databases

in Forensic DNA Analysis

Prepared by  

Human Forensic Biology Subcommittee

Version: 2.1

December 2023

Disclaimer:

This OSAC Proposed Standard was written by the Human Forensic Biology Subcommittee of the

Organization of Scientific Area Committees (OSAC) for Forensic Science following a process that

includes an open comment period. This Proposed Standard will be submitted to a standards

developing organization and is subject to change.  

There may be references in an OSAC Proposed Standard to other publications under

development by OSAC. The information in the Proposed Standard, and underlying concepts and

methodologies, may be used by the forensic‐science community before the completion of such

companion publications.

Any identification of commercial equipment, instruments, or materials in the Proposed Standard

is not a recommendation or endorsement by the U.S. Government and does not imply that the

equipment, instruments, or materials are necessarily the best available for the purpose.
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Version

No.

Issue Date Section Reason

2.0 April 6, 2021  ‐‐  Added to the OSAC Registry and publicly announced.

2.1 December 22, 2023 All Format and font updates only. No content changes made.

 
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Foreward

Monitoring contamination is critical to preserving the integrity of forensic DNA results.   As part

of an overall quality assurance program, forensic DNA laboratories have a comprehensive

approach to monitoring for DNA contamination.    The primary component of a laboratory’s

approach to detecting possible contamination is the incorporation of quality control samples

such as reagent blanks, extraction controls, and amplification controls. These controls are used

to monitor for contamination introduced during the DNA testing process, but do not directly

assess the presence of contaminants in individual case samples. An elimination database is an

additional component that can be used to directly evaluate case samples for possible

contamination. Elimination databases are important to avoid providing misleading information

to investigators, entering errant DNA profiles into CODIS, or, more broadly, to detect

contaminants.  It is essential for each laboratory to develop policies regarding the generation,

management, and searching of the elimination database. Laboratories should ensure that their

practices adhere to and are in compliance with all applicable laws within their jurisdiction.

Keywords: DNA elimination database, quality assurance, contamination
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Table of Contents

1 Scope .....................................................................................................................................6

2 Normative References........................................................................................................... 6

3 Terms and Definitions............................................................................................................ 6

4 Best Practice Recommendations ...........................................................................................6

Annex A.......................................................................................................................................11

 
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Best Practice Recommendations for the Management and Use of Quality Assurance DNA

Elimination Databases in Forensic DNA Analysis

1 Scope  

This document provides best practice recommendations for the collection, storing, searching,

and retention of DNA elimination samples and/or profiles in a quality assurance database.  This

document addresses the use of elimination databases as one component of a comprehensive

approach to detect and monitor contamination.  

2 Normative References

There are no normative references for these best practice recommendations. Annex A, contains

informative references.

3 Terms and Definitions

3.1

contamination

Exogenous DNA or other biological material in a DNA sample, PCR reaction, or item of evidence;

the exogenous DNA or biological material could be present before the sample is collected or

introduced during collection or testing of the sample.

3.2

elimination profile

A DNA profile from an individual whose access, role, or activities might result in DNA

contamination. The term also includes profiles associated with consumables and positive

controls.   

3.3

elimination database

A searchable collection of elimination profiles.

4 Best Practice Recommendations

4.1 The laboratory should maintain and use an elimination database in accordance with the

various laws within its jurisdiction.

4.2 The laboratory should have elimination database policies that address the following:  

a) the purpose of the database;

b) the generation, management, and searching of the database;
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c) personnel who have access to the database;

d) the evaluation and resolution of candidate matches; and

e) the reporting of positive associations.

4.3 An elimination database should be comprised of profiles from the following categories.  

4.3.1 Individuals who have direct contact with the evidence, such as:

a) Personnel in the forensic biology/DNA unit of the laboratory

b) Laboratory personnel who may handle and/or examine evidence prior to the transfer of

an item to the forensic biology/DNA unit

c) Investigative or crime scene personnel who collect or handle evidence

d) Medical examiner’s office personnel, sexual assault nurses, and other hospital staff who

may come in direct contact with and handle evidence

e) Laboratory or investigative agency staff who may handle outer evidence packaging

f) Laboratory custodial staff who may enter the forensic biology/DNA unit

4.3.2 Individuals with more limited contact with the evidence, such as:

a) Laboratory staff regardless of work unit or access level to the forensic biology/DNA unit

b) Investigative agency staff who may be present at the crime scene

c) Visitors, maintenance staff, or vendor staff who may enter the forensic biology/DNA unit

4.3.3 Additional DNA profiles, such as:

a) Profiles attributed to consumable manufacturing staff

b) Unattributed contamination profiles

c) Laboratory positive control profiles

4.4 All individuals providing samples for the elimination database should sign and receive an

information sheet that includes at a minimum:

a) Organization managing the elimination database

b) Purpose of the elimination database

c) The extent to which the samples will be used (e.g. will only be used for quality assurance

purposes and not for medical research purposes)
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d) Privacy protections

e) Acknowledgement that associations to their profile will be evaluated and may be

reported

f) The retention policy for the samples, raw data, and the resultant profile

4.5 Samples should be typed using the test kit(s) currently in use.

4.5.1 Before a laboratory changes or adds a new typing kit,samplesfrom individuals who come

in direct contact with evidence should be retyped with that kit.

4.5.2 Samples from individuals who do not come in direct contact with evidence need not be

retyped unless needed to assess potential contamination events.

NOTE:  A change in typing test kit does not preclude maintaining profiles typed with previous

typing test kits.

4.6 All samples tested and profiles entered into the elimination database should be

designated with a unique identifier.   

4.6.1 Profiles from known individuals should not be labeled with personally identifiable

information but should be traceable to the individual from whom the sample originates.

4.6.2 For samples originating from outside of the laboratory, the traceability may be

maintained by an external entity.

4.7 The laboratory should have written policiesregarding the management of the elimination

database that address the following:   

4.7.1 Access to the samples and data should be controlled and limited to authorized users to

maintain confidentiality and prevent accidental or intentional misuse.

The policy should consider differentiating access levels between those individuals who can view

the matches and those individuals who can access the traceability to determine the individual

who donated the sample. This may be the same individual or different individuals but should be

defined in the policy.

4.7.2 The security of all samples and data in the elimination database should be maintained in

a manner that protects against accidental loss, destruction, or manipulation/compromise.

4.7.3 The laboratory should have a mechanism to ensure version control of the elimination

database.
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4.7.4 The retention time for samples and data should be clearly defined in laboratory policy.   

It is recommended to retain original samples for the purpose of retesting as new relevant testing

methodologies become available. For retention of profiles in the elimination database,

consideration should be given to the potential for contamination risk and the expected time

period the material handled by individuals will be in the system. It may be reasonable to archive

some profiles and make them available for searching only for selected cases (e.g., cold cases,

appeals, and post‐conviction cases).

4.8 The laboratory should have policies that address the searching parameters and matching

criteria for the elimination database.

4.8.1 The policy should describe the categories of profiles (e.g., single source and/or mixture

evidentiary profiles, deduced evidentiary profiles, reference profiles) that will be searched

against the elimination profiles.

When feasible, it is recommended that all evidentiary profiles deemed interpretable but not

associated to a reference profile be searched against the elimination database.  

4.8.2 The policy should addressthe search stringency and match criteria for detecting potential

associations, for example, by a minimum statistical threshold, a minimum number of matching

loci, or the discrimination power of the profile being searched.  The selection ofsearch stringency

and match criteria will be guided by the intended goal of the search.   

Search parameters and the extent of the information contained in the results may vary

depending upon the level of searching that will be conducted as well as the number of profiles in

the database.

For example, one type of search can be designed with a low association threshold to trigger an

investigation. This type ofsearch is effective at detecting true contaminants, even when the level

of contamination is very low.  The benefit is that this approach could be relied upon as a primary

means of detecting contamination.   Increases in testing sensitivity, however, are paired with

decreases in specificity, and the laboratory could expect increased instances of investigating

adventitious matches.    This would especially be true for complex profiles, very low‐level

contributors to mixtures, and large elimination databases.

An alternate type of search with a high association threshold would be effective at detecting

gross contamination.  A laboratory may choose this approach when, for example, the elimination

database search is meant to prevent profiles from entering a government database such as

CODIS. Benefits of this approach include fewer investigations of adventitious associations, even

with larger database sizes. Such an approach could not be used or relied upon to detect lower

level contamination.   
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4.8.3 The elimination database should be searched prior to a laboratory report being issued,

and that search should be documented in the case record.

4.9 The laboratory should have the following policies addressing the investigation of possible

associations resulting from an elimination database search:

4.9.1 If contamination is a plausible explanation for the association, the laboratory should

follow its quality system protocols.

If an association is made to non‐laboratory personnel, it is incumbent upon the laboratory to

report this information to the applicable agency or consumable manufacturer for potential

retraining or process improvement.

4.9.2 For associations in which contamination is not a plausible explanation, it may be

necessary to disclose the association for possible investigation by law enforcement.

4.9.3 Laboratory policy should specify how to address situations in which an association

remains ambiguous and cannot be resolved as either contamination or adventitious.

4.10 The laboratory should have the following policies for reporting elimination database

associations that are not resolved by re‐testing:

4.10.1 If an elimination database association is made after a report has been issued, the

laboratory should communicate the association to the recipients of the original report.   

4.10.2 Documentation of elimination database associations should be retained or referenced in

the case record and maintained in a centralized log.

   
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Annex A

(informative)

Bibliography

1] SWGDAM Interpretation Guidelines for Autosomal STR Typing by Forensic DNA Testing

Laboratories.  Available at www.swgdam.org.

2] SWGDAM Contamination Prevention and Detection Guidelines for Forensic DNA

Laboratories. Available at www.swgdam.org

3] FSR‐P‐302 Protocol: DNA contamination detection‐The management and use of staff

elimination DNA databases.  

4] ISO/IEC 27001:2013 Information technology—Security Techniques—Information security

management systems—Requirements

5] Standard for Interpreting, Comparing, and Reporting DNA Results Associated with Failed

Controls and Contamination Events.  ASB Standard #

6] OSAC Proposed Standard 2020‐S‐0004 Standard for Interpreting, Comparing, and Reporting

DNA Test Results Associated with Failed Controls and Contamination Events (Update link

when published).

7] Manufacturer contamination of disposable plastic‐ware and other reagents‐An agreed

position statement by ENFSI, SWGDAM, and BSAG. FSI:Genetics.  July 2010, Vol. 4, issue 4.

pp. 269‐270

8] Cecilia Crouse and David Kaye (2001), The Retention and Subsequent Use of Suspect,

Elimination, and Victim DNA Samples or Records: A Report to the National Commission on

the Future of DNA Evidence. SSRN Electronic Journal. 10.2139/ssrn.2050686.

9] Martine Lapointe, Anita Rogic, Sarah Bourgoin, Christine Jolicoeur, Diane Séguin, Leading‐

edge forensic DNA analyses and the necessity of including crime scene investigators, police

officers and technicians in a DNA elimination database, Forensic Science International:

Genetics 19 (2015) 50–55

10] David H. Kaye, GINA's Genotypes, Michigan Law Review First Impressions, Vol. 108, Jan. 2010,

pp. 51‐57, available at https://papers.ssrn.com/abstract_id=1551476 and

https://repository.law.umich.edu/mlr_fi/vol108/iss1/5/