Investigating a 19 year old homicide

The use of DNA profiling is a well documented and widely used technique in crime scene investigations. Rapid advances in technology for DNA sequencing have provided crime fighters with valuable additional tools for investigations and led to increased prosecutions. While the use of DNA sequencing is heavily relied upon, it remains a rapidly evolving field, and scientific advances to improve methods and ensure accuracy are of great importance for the future development of this crucial tool in criminal justice.

Published in Investigative Genetics this month, Melton et al. report on the effective use of mitochondrial DNA (mtDNA) analysis of small hairs. They provide evidence suggesting that it is possible to extract reliable data for mtDNA analysis from hairs measuring less than 0.5cm in length from a homicide case which arose 19 years ago. Prior to this research, it was commonly thought that gaining evidence from hairs of this size would not provide sufficient data for mtDNA analysis, and based on this assumption, some labs will only accept hairs of over 2-3cm for analysis. However, as Melton et al. demonstrate, the size of the hair is of less importance than its condition, in terms of environmental degradation. They claim that this study ‘indicates that even the smallest probative crime scene hairs are suitable for mitochondrial DNA analysis and can provide useful data’.

This research represents an important milestone in forensic genetics, and demonstrates that smaller samples may be able to yield significant results in aiding criminal investigations.  These results open a  new realm of possibility in the investigation of crime scene evidence, whereby law enforcers will need to trust scientists and the forensic community to select and profile the most valuable and relevant samples.

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