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New Report Recommends Policies for Improved Preservation of Biological Evidence

DHS Image of Evidence Collection
A law enforcement officer collects evidence from a simulated crime scene during training for handling of hazardous biological materials.
Credit: Center for Domestic Preparedness, Federal Emergency Management Agency, U.S. Department of Homeland Security

All states should have laws ensuring that criminal justice systems properly handle, store and retain forensic biological evidence, according to a new report* from the National Institute of Standards and Technology (NIST). NIST's guide, Biological Evidence Preservation: Considerations for Policy Makers, encourages legislators, judges, law enforcement officials, crime laboratory managers and other policy makers to implement or update laws that support best practices in this critical area.

"While 43 states and the District of Columbia have enacted statutes related to the preservation of biological evidence, policies and procedures can be enacted in states that currently have no laws," as well as states looking to improve existing legislation, according to the NIST report.

Biological evidence refers to two types of evidence commonly recovered from crime scenes or collected during criminal investigations: biological samples such as blood, semen and other bodily fluids; hair; tissue; bones and teeth; or items containing biological material such as a bloody T-shirt. An earlier NIST report, The Biological Evidence Preservation Handbook: Best Practices for Evidence Handlers,** detailed a set of best practices to help ensure biological evidence is properly stored to avoid contamination, protected against premature destruction or degradation, and accurately tracked to prevent loss.

The new guide for policy makers discusses key issues that influence and drive policies in this area. Based on a thorough examination of existing state statutes, current trends, law, scientific literature and expert opinions, the authors make nine recommendations for actions that support best practices for preserving biological evidence.

"Biological evidence can carry a lot of weight in solving crimes, but if you can't find it or find it in an unusable state, it won't help you conduct the necessary forensic analyses to administer justice fairly," said Shannan Williams, project manager in the NIST Forensic Science Research Program.

Among the report's policy recommendations are that each state require:

  • The establishment of an authoritative body to define and enforce standards related to biological evidence preservation;
  • Biological evidence be stored in appropriate environmental conditions, based on known scientific practices;
  • Evidence be retained according to timetables based on the type of crime and the status of the case; and
  • A means for defendants or petitioners to seek recourse in cases where it has been judicially determined that a denial of access to biological evidence has occurred.

Both reports were authored by the Technical Working Group on Biological Evidence Preservation, a group of 20 experts from various forensic, law enforcement and scientific disciplines, as well as legal scholars, medical personnel and representatives of relevant professional organizations.

The National Commission on Forensic Science, coordinated by the Department of Justice and NIST, has chosen to address this topic through the creation of an Evidence Retention and Preservation Working Group. The working group is developing a document that will summarize the status of scientific and legal issues surrounding the retention and preservation of biological as well as non-biological evidence.

The commission plans to discuss policies to support best practices for biological evidence preservation at its meeting in Washington, D.C., from April 30-May 1, 2015. Williams will present the new NIST report to the commission during the meeting. For meeting details and a link to a webcast of the event, go to

To learn more about biological evidence preservation, see the NIST Forensic Evidence Management web page.

* Technical Working Group on Biological Evidence Preservation. Biological Evidence Preservation: Considerations for Policy Makers (NISTIR 8048). 2015,

** Technical Working Group on Biological Evidence Preservation. The Biological Evidence Preservation Handbook: Best Practices for Evidence Handlers (NISTIR 7928).2013,

Released April 20, 2015, Updated January 20, 2023