Current Guidelines
Although each agency and laboratory will have its own standard operating
procedures on how to package biological evidence, there is a fairly general structure that
is followed. The Technical Working Group on Biological Evidence Preservation
(TWGBEP) released a handbook on the best practices for biological evidence preservation
in 2013. This handbook outlines recommended procedures for packaging and storing
biological evidence from the initial collection and packaging until its final disposition (3).
One of the most common practices is to dry all biological evidence prior to
packaging, excluding some samples obtained from a medical office or directly at the crime
laboratory, such as drawn blood. However, some samples cannot be readily dried before
packaging and/or transport is necessary. These samples, as stated by TWGBEP, should be
placed in a plastic bag to avoid the wet biologic on that item from transferring to another
piece of evidence, which could lead to cross-contamination of other items or surfaces. This
suggestion is given with the caveat that if the wet sample remains in this packaging long