The managing scientist of Queensland's forensic lab has denied deliberately steering police towards a process that failed to test crime scene samples with low amounts of DNA.
Managing scientist Cathie Allen was repeatedly accused of lying in her evidence on Friday, as she was questioned about the 2018 options paper that led to low DNA samples not going through an automatic "microcon" process.
The samples that fell below the threshold were labelled DNA insufficient for further processing.
"It's not a lie, I'm not a liar, I'm not lying," Ms Allen told Commissioner Walter Sofronoff via video link.
Her response came after counsel assisting Michael Hodge, KC, pressed her about the paper purportedly designed to inform police about the consequences of changing lab processes.
It included two important figures about how many samples would be affected, one of 10 per cent relating to "warm links" and one of less than two per cent relating to "cold links".
Warm links can refer to a suspect's profile found on items from a crime scene, and cold links are hits on the database for people previously unconnected with the case.
One option was a pause in processing for a group of samples that weren't yielding great success, and police could advise about whether or not to proceed in specific instances, Ms Allen said.
She denied the paper deliberately highlighted the smaller figure to sway police.
"This was a (Queensland Police) decision, if they wanted to keep going with option one, then that's what we would have done," she said.
"This was a change for QPS that had ramifications for them, so they needed to make those decisions because they own the samples."
Ms Allen was later taken to a December 2021 email from QPS Inspector David Neville containing a spread sheet with results from samples labelled DNA insufficient after further work was requested by police.
Of 33 samples examined in the case, 10 returned a result with persons identified with a likelihood ratios of greater than 100 billion.
Insp Neville asked for information about the successful likelihood of success in normal case work for the low DNA samples.
In a subsequent response, Ms Allen referenced monitoring done by the lab and review of a larger data set that found "a very small percentage of samples" may provide some type of DNA profile.
Questioned about what the monitoring involved or what the data set referred to, Ms Allen said she couldn't recall.
"I know that I would not have lied, but I cannot think of what I was referring to," she said.
Ms Allen was also questioned about how it came to be that samples deemed the highest priority by police fell into the same testing regime if they fell below the DNA threshold.
She told the inquiry about a conversation in 2018 with Superintendent Dale Frieberg, where the officer agreed to treat priority one and priority two samples the same, but it was never confirmed in writing.
"Even the options paper had not suggested discontinuing (auto microconing) for priority one samples," Mr Hodge said.
Ms Allen said Supt Frieberg had "been very clear" with her.
"If they were going to go with that option ... priority one samples and priority two samples would be treated the same," she said.
Her evidence continues.
