Roxanne Zascavage: DNA sequencing: changing the game of forensic investigation

Spotlight session: Roxanne introduced herself as a forensic DNA investigator, whose work revolved around DNA sequencing technologies for forensic applications. Roxanne’s opening slide featured a quote from “the most famous forensic investigator” – Sherlock Holmes. The quote centred around the identification of blood from a dried sample, but, Roxanne noted, the same quote about changing the game of criminal investigation could be applied to DNA sequencing.

Roxanne went on to discuss the broad range of applications within forensics to which DNA sequencing could be applied – including but not limited to criminal investigation, missing/unidentified persons, paternity tests, immigration disputes, bioterrorism and familial searching.

Moving to the history of DNA testing in forensics, Roxanne described the first utilisation of these techniques in the UK in the mid 1980s, to exonerate an innocent man and identify and convict another, before broader expansion to the US in 1987 and the DNA Identification Act in 1994 that allowed suspects to have samples collected and information logged in a database.

Putting this into context and taking a step back from DNA specifically to all evidence, Roxanne showed a picture of the 9/11 disaster, where a team deployed immediately following the event processed 21,000 remains in an attempt to identify the several thousand missing persons. In terms of evidence, Roxanne posed the questions: what happens to evidence when it is burnt? Left out in the sun? Or discovered many years later? Most evidence, Roxanne explained, is degraded and rendered useless – but mitochondrial DNA perseveres making it an ideal candidate for analysis of evidence. Of the 9/11 individuals that have been identified, the last three were named in 2015, 2017 and the final just two months ago, demonstrating that as technology advances and nucleic acids can be analysed even at very low abundance, more and more cases can be resolved. Connecting that mitochondrial DNA to those individuals has been critical to the family and loved ones of the missing people.

Changing tone from disaster to serial murders, Roxanne reiterated that as long as we have remains we can work towards identification. However, databases mostly currently include only data from those that have been convicted, although these rules vary by state - some include those that have been arrested or permit familial searching.

Roxanne then asked: what do you think of when you think of a serial killer? A white male? Databases in general are heavily biased towards minorities, and this inhibits isolation of suspects. The ideal would be, Roxanne states, to take a sample from a crime scene, run an analysis from start to finish, and obtain all the information you need – but often this is limited by references to identify against. Voluntary databases, though, represent the beginning of a solution to this – as Parabon has been used to solve 20 cases so far, including cold cases. Public databases have no regulation, and this could lead to concerns over safety.

In two years, Roxanne concluded, 90% of Caucasians will be able to be identified by cousins, aunts, uncles, sisters, brothers using these websites and publicly accessible data.