Angelina Keller, a scientist specializing in cold cases, told the Commission of Inquiry into Forensic DNA testing in Queensland, the problem she noticed after changes to the way bone crushing equipment was cleaned at the lab. She became concerned about contamination at Queensland’s forensic lab after a high number of bone and teeth samples failed to yield proper DNA profiles.
She told the commission that Samples taken from the inside of bones and teeth should only contain DNA from one person. But Ms. Keller started getting mixed DNA profiles from bones and teeth from the year 2022. For the first time she found it unusual but then it happened frequently.
Keller said that in July 2019, the laboratory changed the protocols for cleaning bone processing equipment, the inquiry heard. Previously, chisels, hammers and saws were scrubbed by hand in a tub containing water and Tergazyme, a detergent that breaks down DNA. Ms Keller said the change was implemented without testing or consultation with the scientists in the bone unit.
This year in May, Ms Keller noticed the chisels used for bone sampling had developed rust due to the new cleaning process. She said the rust could be retaining DNA and contributing to the contamination of bone and teeth samples.
Ms. Keller also gave evidence about a new extraction method the lab had adopted. She told the inquiry commission that in April 2018, the lab switched from an “organic” extraction method, a manual process requiring a high level of skill to one involving a robotic instrument.
Ms. Keller said she raised concerns with management since she has noticed an increase in the number of low level or no DNA profiles from bones and teeth. She explained that coronial bones tend to have lower levels of DNA and they are dealing with compromised bone samples from which it’s harder to get a full profile.
The inquiry is still in progress and the hearing in the same has been scheduled for December 2022.