Sources used in this document:

Watterson, J., Blackmore, V. & Bagby, D. (2006). Considerations for the analysis of forensic samples following extended exposure to the environment. The Forensic Examiner, 15(4),

19-21.

Authors are all forensic scientists who present a timely discussion concerning the harmful effects that extended exposure to the environment can have on forensic evidence, including its analysis and the interpretation of test results. Because crime scenes may produce less-than-optimum samples of DNA, blood and other molecular-based evidence based on environmental factors such as sunlight, rain, and microorganism growth, authors provide a review of the relevant literature to explain how these constraints must be taken into account when conducting forensic investigations and analyses. In particular, authors emphasize that biomolecular substances such as enzyme and DNA analyses are adversely affected by these environmental factors. While these biomolecular materials may remain amenable to forensic analyses over time if they are properly stored and maintained, extended exposure to environmental elements can cause them to degrade in ways that confound even the most sophisticated technologies. Authors also present a discussion concerning how both biological and non-biological samples are affected by exposure to environmental factors, and how toxicological tests to ascertain time and cause of death can be hampered by these effects. Authors point out, though, that it is possible to interpret the results of forensic analyses of even degraded biological samples if forensic scientists are cognizant of the processes these samples tend to undergo as they degrade. Although some types of samples such as paint chips and glass fragments may not be adversely affected by extended exposure to the environment, other substances such as volatile ignitable liquids tend to evaporate altogether, making time of the essence in gathering evidence and conducting suitable testing protocols. Authors also emphasize, though, that there remains a dearth of timely and relevant guidance in the literature concerning the interpretation of biological samples that have experienced extended exposure to these environmental elements and call for additional research in this area. Taken together, this journal article presents useful guidance for forensic scientists who are confronted with degraded samples as a result of extended exposure to the environment, and note that the nature of crime means that these types of samples will be far more common in forensic scientists' experience than the pristine samples with which they may have been trained.