A 2018 decision not to test crime scene samples with low amounts of DNA that fell under a certain threshold is the focus of a commission of inquiry in Brisbane.
Inspector David Neville told a previous hearing he initially understood the chance of obtaining a usable DNA profile among the samples was less than two per cent.
The success rate for a group of samples sent for further testing at the request of Queensland police was more than 30 per cent.
Acting executive director of Forensic and Scientific Services Queensland, Lara Keller, was copied into an email chain in December 2021 in which police outlined their concerns.
Ms Keller said she failed to understand that the issue put forward by police was whether the process in place maximised the chances of solving crimes.
"I did not put that into context at the time because I was under the impression a review was going to be done and ... there were no cases that were going to be compromised," she told Monday's hearing.
Ms Keller, who has been in the role for about a year, said she did not understand the 30 per cent figure put forward by police.
"I was being told that ... the 1.86 per cent was the figure in question and there was a safety net in that at any time a scientist or a member of the police service could request full testing," she said.
"I didn't really understand the 30 per cent success rate because I was being presented with the 1.86 on a regular basis with that caveat that essentially nothing is missed."
Queensland Health acting director-general Shaun Drummond previously told the inquiry he was given a "disingenuous" representation of the consequences of the 2018 decision to change thresholds.
The inquiry continues.
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