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CONTAMINATION OF FORENSIC SPECIMENS

Saturday 8^th 11.05am

Dr Rebecca Heyes

Rebecca Heyes is the Manager of the Biological Examination Branch of the Forensic Services Department of Victoria Police. She commenced her career as a forensic scientist in 1998 after completing a PhD in molecular biology at the University of Melbourne’s Department of Medicine. As a racticing forensic scientist her areas of expertise include biological examinations, genetic typing of biological material and crime scene examination. She has worked as a forensic scientist in both Australia and the United Kingdom and has presented her findings and given her opinion on scientific issues raised in the courts of Victoria on numerous occasions.

OVERVIEW

Contamination of Forensic Specimens – Rebecca Heyes

Specimens are separated into different rooms for testing
Locard’s Principle
DNA typing: 10 hypervariable (distinct) sites
- Make copies of DNA and label copies
- The more of the ten that match the higher probability of a match
- e.g. 3 matches = 1 in 80,000 / 10 matches = 1 in 110million
External swabs: high danger of contamination
Internal swabs: low danger of contamination as we have more DNA
Skin cells have less DNA than saliva or semen
LCN:
- Low copy number DNA
- Need very strict contamination precautions
- State of the art DNA testing
MAYBE we should consider sending DNA reference sample from the collector??