Trace DNA analysis: Do you know what your neighbour is doing?

Abstract 

Since 1997 the analysis of DNA recovered from handled objects, or ‘trace’ DNA, has become routine and is frequently demanded from crime scene examinations. However, this analysis often produces unpredictable results. The factors affecting the recovery of full profiles are numerous, and include varying methods of collection and analysis.

Communication between forensic laboratories in Australia and New Zealand has been limited in the past, due in some part to sheer distance. Because of its relatively small population and low number of forensic jurisdictions this region is in an excellent position to provide a collective approach. However, the protocols, training methods and research of each jurisdiction had not been widely exchanged. A survey was developed to benchmark the current practices involved in trace DNA analysis, aiming to provide information for training programs and research directions, and to identify factors contributing to the success or failure of the analysis.

The survey was divided in to three target groups: crime scene officers, DNA laboratory scientists, and managers of these staff. In late 2004 surveys were sent to forensic organisations in every Australian jurisdiction and New Zealand. A total of 169 completed surveys were received with a return rate of 54%. Information was collated regarding sampling, extraction, amplification and analysis methods, contamination prevention, samples collected, success rates, personnel training and education, and concurrent fingerprinting.

The data from the survey responses provided an insight into aspects of trace DNA analysis, from crime scene to interpretation and management. Several concerning factors arose from the survey. Results collation is a significant issue being identified as poor and differing widely, preventing inter-jurisdictional comparison and intra-jurisdictional assessment of both the processes and outputs. A second point of note is the widespread lack of refresher training and proficiency testing, with no set standard for initial training courses. A common theme to these and other issues was the need for a collective approach to training and methodology in trace DNA analysis.

Trace DNA is a small fraction of the evidence available in current investigations, and parallels to these results and problems will no doubt be found in other forensic disciplines internationally. The significant point to be realised from this study is the need for effective communication lines between forensic organisations to ensure that best practice is followed, ideally with a cohesive pan-jurisdictional approach.

Keywords: Trace DNA, DNA profiling, Survey, Methods, Crime scene investigation, Forensic management