Hennepin County DNA lab to resume work following sample contamination
MINNEAPOLIS (FOX 9) - More than a month since the Hennepin County Crime Lab halted DNA testing, they believe they’re getting close to resuming, likely in the next two to three weeks.
They’ve identified the likely source of a DNA contamination. And they staunchly defend the integrity of their work.
"There is not a reason to think that there’s anything wrong with the DNA testing process," said Allison Dolenc, the lab’s DNA Section Supervisor.
Dolenc sat down with FOX 9 to walk through exactly what caused them to pause DNA testing on Sept. 17, and to clarify any misconceptions it may have brought. She insists that no one should take this as there are any errors in the work they do.
"I would say to anyone that the integrity and reliability of the DNA results that we perform, and the forensic science laboratory, are of the utmost quality," Dolenc said.
She explained in detail what happened back in September that set off alarm bells. An unknown DNA profile appeared in a control test, what’s known as a re-agent, a neutral liquid that should not have DNA in it at all.
Then, they discovered this matched an unknown DNA profile that appeared alongside other profiles in a test of evidence in 2022.
At the time, they thought this was additional DNA on that piece of evidence. Now, they realized it could only have come from the testing supplies.
When they looked at more than 50,000 samples dating back to 2016, they found this exact unknown DNA profile in about 30 of those samples, but at random intervals.
When initially reported back in September, it was thought to be as many as 75 cases, but that number has since been clarified to be less than half that.
The only explanation is that DNA came in minute amounts on the disposable lab supplies, such as tubes and test trays.
"You’ve ruled it a certainty that it’s coming in on these plastic consumables from a supplier? That is what we’ve narrowed it down to, yes," said Dolenc.
Eight other crime labs across the country have since found this exact same unknown DNA profile. And they all use the same supplier.
The supplier and its manufacturer are in the middle of their own investigation to determine which employee somehow contaminated plastic as these supplies were being made.
But that extra DNA, Dolenc stresses, cannot invalidate any of the tests they’ve done.
"There is not a possibility that this DNA profile falsely identified anyone," Dolenc said.
All it could do, she says, is potentially dilute the samples to prevent a positive identification.
But in cases where DNA was identified, it could not have led to that result being inaccurate. It’s simply an additional profile.
The lab is currently running some DNA tests on plastic lab supplies from a different company to make sure they don’t have the same problem. So far, all is clean.