Police inspector tells inquiry he'd voiced concerns over Queensland DNA lab testing

Queensland Police Inspector David Neville has told an inquiry into failures at a state-run DNA testing lab of the moment he became deeply concerned about evidence being missed.

"I was forming a suspicion that we were missing out potentially on profiles or evidence," he said on Wednesday.

The police inspector warned the community was at risk over testing issues at Queensland's troubled lab, which delayed the capture of a murder suspect last year.

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The murder was solved in November only after DNA samples were re-tested and it raised alarm bells at the highest level.

"I was absolutely of the firm belief now that there was a problem," Neville said.

The inquiry into failures at the lab heard Neville pleaded with it to review its testing thresholds on at least three occasions last year.

An email to a superintendent, shown to the inquiry, flagged the problem and warned a "failure to take timely action could place people in the community at risk by allowing a perpetrator to go unidentified".

The inquiry has heard there are around 7000 samples from major crimes that still need to be re-tested.

The question that remains unanswered now is how many of those could have already been solved if Queensland's testing procedures were different.

DNA expert Professor Linzi Wilson-Wilde told the inquiry that DNA testing thresholds should be flexible, not fixed.

"It all depends on the case circumstances," she said.