Identifying the invisible.

New forensic technology developed by Flinders University is transforming crime scene investigations.

It’s now possible for people to be identified from DNA traces taken from objects that previously could not be read accurately – including fired cartridge cases, detonated explosives and manufactured illicit drugs – thanks to a high-precision portable testing system. The breakthrough is set to have sweeping international ramifications for supporting the success of criminal prosecutions.

“We can see cells on these items through our system, then use a microscope to pick the cells off an item, put them in a tube, analyse the DNA and generate a profile – and no-one else in the world can do that. It’s a game changer,” says Professor Adrian Linacre, Chair in Forensic DNA Technology at Flinders University.

Until now, crime scene investigators applied swabs to surfaces where they presume DNA will be deposited, but without knowing for certain because DNA is not visible to the human eye. These samples are taken to laboratories, where they are subjected to an extensive laboratory procedure to isolate then quantify any DNA. It’s a costly, laborious process that can take up to three hours to obtain results – and a vast majority of swab results come up negative. One state police force estimates it spends about $7.5 million a year on swabs where no DNA was present.

New research driven by Professor Linacre and his team at Flinders University allows investigators to see exactly where DNA is located in an instant, using dye sprayed from an aerosol canister at a crime scene for an instantaneous identification of deposited skin cells.

Professor Adrian Linacre

Email

“We can spray an item or area with the DNA-binding dye, see cells light up, and then be confident that the sample we will collect actually contains DNA. DNA becomes visible in five seconds, thanks to an inexpensive and portable fluorescence digital microscope, which allows easy viewing even in ambient light at an investigation scene. Then we take the swab away for more serious analysis to make an accurate DNA profile.”

The inspiration for this new system came to Professor Linacre three years ago, when he made a thumb print on a glass slide, applied dye and, through a powerful microscope linked to a computer, he could see illuminated skin cells on the screen. In this moment, he realised that testing for DNA could be done on site with portable devices rather than in laboratories – saving great time and money, and increasing the success rate of DNA profiling.

This discovery will have global implications in an emerging science that first recorded DNA profiles generated from touched objects in 1997. The 13-person Flinders University team – which also features chemistry expert Professor Paul Kirkbride – is now recognised as a world leader in this type of DNA research. Their 17 published research papers during the first half of 2022 verify their exciting initial findings and underline the legal validity of the new system to support effective crime investigation.

“We can’t afford for any of this to be wrong or have errors. These can’t just be bright ideas. The research results have to be peer reviewed and irrefutable. It has to stand up in a court of law,”

Professor Linacre’s trademark rigour was developed during 17 years of crime scene investigations in Glasgow, and has not waned since commencing his research career with Flinders in 2010. “We can’t afford for any of this to be wrong or have errors. These can’t just be bright ideas. The research results have to be peer reviewed and irrefutable. It has to stand up in a court of law,” he says, noting that the Flinders team has been teaching the system to crime scene investigators from the NSW and WA police forces, and attracted recent international attention from Finland Police.

Professor Linacre’s team is now researching the so-called shedder status of different people, measuring the propensity of a person to shed skin cells and deposit their DNA. Three grades of shedders have been identified, from heavy shedders depositing many cells with every touch, to very light shedding. Rigorous testing has also shown that a person’s shedding status is consistent across all parts of their bodies (from both left and right hands, for example) and does not change over time.

“To identify someone’s shedder status is another means of more accurately identifying a DNA profile that will be able to stand as irrefutable evidence in court.”

Professor Linacre is also confident of unlocking information about secondary DNA transfer to trace the history of DNA on an object and identify specific timelines of when each deposit was made, leading to positive identification of people in exact locations at specific times.

“It’s a very significant piece of the larger forensic puzzle,” he says. “Our work brings closure. It’s a relatively immediate science. Each piece of research leads us through another door – and onward.”

Professor Adrian Linacre