A decision to change testing processes in Queensland that means thousands of DNA samples are being re-tested did not reach the minister-in-charge at the time.
Deputy Premier Steven Miles was health minister in 2018 when the threshold limits were changed at the state-run forensics lab.
Many DNA samples that fell below the threshold were not tested as thoroughly as they could have been, and now Queensland Police are reviewing cases in the hope further analysis could yield a partial or full profile.
The shortcomings were laid out in an interim report by an inquiry into Forensic DNA Testing in Queensland, released on Wednesday.
Mr Miles says he was not previously aware of the issues raised.
"Obviously they're very concerning. In my experience the pathology staff that I dealt with were incredibly diligent," he said on Friday.
"I'm as surprised as anybody to hear these concerns."
Mr Miles described the threshold change as a technical decision typically made by scientific services.
"If these concerns were raised at that time, I would have taken them very seriously," he said.
He dismissed opposition calls for current Health Minister Yvette D'Ath to lose her job.
Two senior staff members at the forensic lab have been stood down pending the results of the investigation.
Deputy Leader of the Opposition Jarrod Bleijie said the testing shortfall was a nightmare for the state's justice system and victims of crime.
"Two public servants for the biggest maladministration that we have seen in a generation in this state is not going to cut it," he said.
The inquiry's full report is due in December and it will hold public hearings next week.
Commissioner Walter Sofronoff KC said the first hearings would consider the threshold changes at the heart of the interim report.
Public submissions are open until October 21.
"I want victims of crime, defendants, lawyers, forensic experts and both current and former public servants and police to bring relevant matters to my attention," Mr Sofronoff said.
