Thousands of Queensland DNA crime scene samples went untested in controversial lab decision, inquiry hears

On its final day of public hearings, the Commission of Inquiry into Forensic DNA Testing in Queensland has heard thousands of crime scene samples were not progressed for testing after a controversial 2018 change.

The now-scrapped decision not to process samples under a certain threshold — labelled “DNA Insufficient for Processing” or “DIFP” — has been at the centre of inquiries.

It comes after weeks of public hearings probing the troubled state-run forensic laboratory.

The decision was made in 2018 and abandoned when the Queensland government ordered the commission of inquiry earlier this year.

Counsel assisting the inquiry Susan Hedge on Friday questioned expert witness South Australian Professor Linzi Wilson-Wilde, who told the inquiry about 4,000 samples had ultimately not been tested each year.

Data provided by Queensland Health broke down how many samples were received each year, and how many of the samples classified “DIFP” were in fact processed further.

“Looking at the total samples received … being between 20,000 and 25,000 samples, those numbers which are about 20 per cent, equates to about 4,000 samples every year that weren’t progressed?” Ms Hedge asked.

“Yes, that’s what the data indicates,” Professor Wilson-Wilde replied.

“That data shows the effect of those thresholds over this period of time, in terms of what was not tested?” Ms Hedge asked.

“Correct.”

Samples below the threshold were labelled “DIFP”, and other samples where no DNA was detected were also not progressed further.

Year

Total samples

Not progressed

2018

25,761

18.8 per cent

2019

23,852

26.9 per cent

2020

25,416

23.3 per cent

2021

23,702

22.6 per cent

2022

27, 080          

20.2 per cent

The inquiry was also told that of the samples below the threshold that were progressed for testing, the success rate in getting a DNA profile was always above 50 per cent — and in 2022, as high as 97 per cent.

The commission of inquiry is set to deliver a final report by December 13.

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