Preserving Biological Evidence
Written by Kristi Mayo   

Updated May 2, 2013 — Download the Biological Evidence Preservation Handbook here!

EVIDENCE CUSTODIANS and law enforcement managers will soon have access to a resource that has long been needed and desired in the United States: a definitive guide to the handling of biological evidence.

That guide, The Biological Evidence Preservation Handbook: Best Practices for Evidence Handlers, was produced by the Technical Working Group on Biological Evidence Preservation. The working group, co-sponsored by the National Institute of Standards and Technology (NIST) and the National Institute of Justice (NIJ), convened in August 2010 and met nine times during a two-year period.

Members of the 23-person group included law enforcement managers, a property manager, a representative from the Innocence Project, a law professor, a crime scene investigator, a criminalist, and a research biologist. They merged their varied backgrounds to “create best practices and guidance on how to properly preserve, process, store, and track biological evidence to safeguard against contamination, premature destruction, or degradation.”

Melissa Taylor, management and program analyst for the Forensic Science Program at NIST’s Law Enforcement Standards Office (OLES), said the working group was greatly needed by the forensic community because of the disparate nature of evidence-handling procedures across the criminal justice system in the United States.

“Agency investments in new testing equipment and improvements to forensic analysis techniques are wasted when evidence cannot be found or is not properly preserved,” said Taylor. “The criminal justice system relies on biological evidence when determining innocence and guilt and proper evidence management plays a critical role in ensuring that justice is ultimately served.”

Not inventory-control specialists

Names, places, and circumstances change, but the headlines appearing regularly in U.S. media outlets are mostly the same: evidence turns up misplaced, mishandled, stolen, or destroyed. Taylor and others are quick to point out that blame should not be placed on evidence custodians. Instead, they point to a complete lack of standardization in this area of forensic science.

In the introduction to the new handbook, the working group writes, “Many law enforcement agencies do not properly address, recognize, or support the efforts of their property rooms. While these agencies bear ultimate responsibility for maintaining the integrity of the evidence, the real problem lies with a systemic failure to properly account for evidence from collection through final disposition.”

In simplistic terms, a property and evidence room is a warehouse of “stuff” that must be inventoried, tracked, and managed. Joseph Latta, executive director and lead instructor with the International Association for Property and Evidence, Inc. admitted it is not fair to expect a law enforcement specialist to come to their job with a skill set that allows them to manage such an operation.

“Police departments are overseen by police managers,” said Latta. “What experience do most police managers have in taking care of a warehouse of evidence? The answer is: Almost none. And if they do figure it out, they often get promoted, transferred, or they retire. So there is a constant change of philosophies, and those philosophies on how we run our property room have been based on that individual’s expertise.

“How do we do a good job in the property room managing this stuff when that’s not our world?”

To answer that question, the Technical Working Group on Biological Evidence Preservation went to the professionals who are engaged daily in the business of inventory and warehouse management.

“We were able to look at commercial entities like Walmart and Target. Their bottom line depends on being able to track and retrieve items,” said Taylor. “We looked at how they apply these technologies and where there were overlaps between the forensic community and these agencies.”

The result of that investigation is a section in the new handbook that details the tracking of the biological-evidence chain of custody. This includes guidance for selecting management and tracking software, automated identification technologies (such as barcoding or radio frequency identification), property room management software, and laboratory information management systems.


Guidance for biological material

Property and evidence rooms have always struggled with questions of where to store, how to store, and how to retrieve and track evidence. But a puzzle that arose relatively recently (i.e. in the past few decades) is the question of how to deal with biological material.

Biological evidence is defined by the working group as “biological material such as hair, tissue, bones, teeth, blood, semen, or other bodily fluids, or trace biological material on clothing, weapons, cigarette butts, etc. that might be collected as part of a criminal investigation.” The handling of this kind of evidence is of particular concern because of the possibility that it might degrade or become contaminated.

Left to their own interpretation of the nature of biological evidence, many law enforcement agencies have resorted to refrigerating or freezing all types of biological evidence. As it turns out, science says this may not be necessary.

“There is a growing movement toward ‘freeze everything. When in doubt, freeze it to preserve it,’” said Taylor. “But when we took a more nuanced look at what are the necessary optimal conditions for various types of biological evidence, the answer wasn’t to freeze everything.” Instead, it might be best practice to simply control the temperature and humidity in a room where biological evidence is stored.

“In a resource-strapped environment, it was actually quite welcoming to hear the scientists say that the added expense of these huge freezers may not be needed.”

The new handbook includes a table that shows the best practices for temporary and long-term storage of the different types of biological evidence. Based on published scientific research, the table indicates that long-term storage in the freezer is best for urine, feces, and liquid DNA extracts. Liquid blood should be stored long-term in a refrigerator. All other types of biological evidence—dry biological-stained items, bones, hair, swabs with biological material, vaginal smears, and buccal swabs—are best stored in a temperature-controlled environment.

Click here to view the table with recommendations for storage of biological evidence!

“That chart is wonderful for people in property and evidence rooms, because now there’s a source that says, This is the best practice,” said Latta. “They should always talk to their crime lab before making any changes to their procedures—but they may also want to make that document a reference for their crime lab to take a look at.”

Another question frequently asked by evidence custodians relates to the required length of time to retain biological evidence. Every state has different statutes or case laws that dictate the category of crimes for which biological evidence should be maintained, the duration of preservation, or cold case provisions.

“That is one of the reasons why the working group couldn’t be more prescriptive in some of the topics covered in the handbook,” said Taylor, referring to the disposition rules that vary widely across states and jurisdictions. “But we brought up disposition because agencies need to reach out to the appropriate people in their jurisdictions to identify an appropriate process for evidence disposition. The handbook provides guidelines that should be followed, but in order to fine-tune this guidance, property and evidence handlers need to meet with local prosecutors, crime lab personnel, and investigators when establishing new policies, just to make sure that any rules that are within your jurisdiction are being followed with relation to how you dispose of evidence.”

Not just property rooms

It is important to note that the scope of the guidelines presented in The Biological Evidence Preservation Handbook go well beyond property and evidence rooms. While an agency’s property and evidence room may be the long-term storage location of the evidence, the recommendations apply also to the holding facility at a courthouse, a secured cabinet at a hospital that contains rape kits, or temporary storage at a law enforcement facility or crime scene unit.

“Very early on, we tried to identify a life cycle for a piece of evidence, starting from a crime scene,” said Taylor. “Where are all the stops that it has to make? And the working group realized that every single one of those places needs guidance on how to properly preserve the evidence.”

Upcoming resources

The Biological Evidence Preservation Handbook: Best Practices for Evidence Handlers will be released during the first quarter of 2013.

In addition to the handbook, the Technical Working Group on Biological Evidence Preservation plans to develop a document that will describe the different evidence tracking technologies available.

Also, a webpage is forthcoming that will serve as a clearinghouse for information useful to those who handle evidence. Such information would include the handbook, links to state statutes regarding the retention and disposition of biological evidence, and links to national and regional associations related to property and evidence rooms.

You can look for all of these resources to go live soon on the OLES website:

About the Author

Kristi Mayo is the editor of Evidence Technology Magazine.

View this article in its original format in our March-April 2013 Digital Edition

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