Anna Davey, Director of Forensic Foundations International, breaks down DNA evidence, forensic concepts, and case limitations in sexual offence matters. Ahead of her presentation at Navigating Forensic Evidence in Criminal Law Matters on Friday, 21 March 2025, she shares key insights into DNA interpretation and its legal impact.
1. Your upcoming presentation will unpack DNA evidence in sexual offence cases. What are some practical takeaways attendees can expect?
Preparation! You can’t wing it. Every sexual offence case is different and the science/medicine input will be different. Take the time to speak with the scientists / medical practitioners involved.
The science/medicine is not scary, it is quite logical, although it does use another language.
Ask ‘How did the biological material / DNA get there?’
There is help out there
2. DNA technology is developing fast. Can you highlight one key advancement or limitation that legal professionals should be aware of, and how it could impact these cases?
The technology currently in use can detect exceedingly small quantities of DNA. Detection. This can be extremely useful but it is a two edge sword. The detection of small amounts of DNA can complicate the interpretation.
Are there alternate explanations see:
3. Presenting DNA evidence in court can be extremely challenging. What do you see as the biggest hurdles, and how can practitioners make complex DNA concepts easier for judges and juries to understand?
4. You’ll also touch on assumptions in DNA reports. How do these scenarios come up?
An accused may suggest that the true offender was an identical twin, a sib or other biological relative. The default assumption is that this is not the case, the lab would need to be informed if this and further interpretations and calculations can be made.
The number of contributors to a mixed DNA profile.
Where relevant the victim / known consenting sexual partner may be one of the contributors.
The Australian Caucasian population database is used for the calculation of the statistics in reference to the true offender (not the accused). If the ethnicity of the true offender is known a different database may be used.
5. Finally, with new techniques emerging and existing limitations persisting, how do you see DNA evidence shaping the future of sexual offence cases and the broader field of criminal law?
DNA is not going away. Scientific and technology advancements will continue to advance the application of molecular biology (genomic DNA, mitochondrial DNA and RNA).
Forensic genealogy is a controversial field – it can provide wonderful intelligence information but at the risk of personal privacy.
Next Generation Sequencing (NGS) or Massive Parallel Sequencing MPS) allows scientists to examine significantly more areas of the DNA, which in turn provides significantly more information including data regarding inherited physical characteristics.
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