Testing of certain DNA samples has been paused due to fears evidence could be lost, an inquiry into Queensland's forensics laboratory has heard.
The inquiry before Walter Sofronoff KC is investigating the 2018 changes that meant crime scene samples ruled to have "DNA insufficient for further processing" were not processed further at the state-run lab.
The lab resumed processing those samples earlier this year.
But the inquiry on Friday heard Queensland Police had requested a pause after concerns a decision made last month, imposing a "blanket" approach towards concentrating samples, could exhaust the DNA.
Police Inspector David Neville, the head of the Queensland Police Service's DNA Management Unit, told the inquiry on Wednesday samples "at the lower end of the end of the range" were at risk.
"A scientist had come forward saying that that blanket policy is risking samples at the lower end of the range … because those samples, if you concentrated them to 35 microlitres, they are still too dilute to get a profile. So, in essence, if you run it, you have now wasted half of the sample," he said.
Under questioning, Senior Sergeant Stephen Foxover confirmed he was aware Queensland Health had made a decision on Friday to halt testing of samples in the "DNA insufficient for further processing" range following QPS's request.
Asked how long he expected the pause to last, he replied: "It's too early for me to say … we're waiting for some information on that."
"Certainly don't want a lengthy pause but I don't have any information on that at the moment [to give you any estimate] about how long it'll take to resolve," he said.
The inquiry was told it "might be months" and the decision was made by acting director-general Shaun Drummond.
A Queensland Health spokesperson said Forensic and Scientific Services had paused some testing "at the request of the police".
"We will resume testing once instructed by QPS. Forensic samples remain the property of police during investigations," they said.
'I don't think it was appropriate'
An interim report by Mr Sofronoff, released last week, found that under an agreement between Queensland Health and the Queensland Police Service, crime scene samples that did not contain quantities of DNA above a certain threshold were not processed further and were reported in witness statements as having "insufficient DNA for analysis".
The inquiry has been told that some of the samples produced profiles and solved crimes when resubmitted by police.
Changes to the DNA testing thresholds were made in 2018 after Queensland Health scientists presented QPS with an options paper.
An internationally-renowned forensics expert — who spent 26 years at the FBI — told the inquiry he did not think the paper was neutral.
"When it comes to the conclusions and options, it's very biased to sort of downgrade the success rate of the samples in this range," Dr Bruce Budowle said.
"I don't think it was appropriate in itself.
"You have to ensure your target audience appreciates the scientific issues, the nuances, the messages, because you're talking to a different audience.
"When I use scientific terms, I could be speaking French to you, or Chinese to you … because you're not used to that jargon."
He told the inquiry that if he was presented with that paper, he would have asked them to go back and do it again because "you've not given me sufficient information for a decision".
The commission of inquiry is due to hand down its final report in December.
