The forensic science lab in Hennepin County is once again fully operational and processing casework after it was shut down for several weeks because scientists at the lab identified a contaminant in their DNA samples.

In a statement, the Sheriff's Office said since halting DNA analysis, its staff reviewed more than 50,000 DNA samples and recommended fewer than 10 cases for retesting. At this point, there has not been any additional request for retesting.

The original contamination was traced back to a plastic plate supplied from a third-party vendor. That vendor is a global provider to forensic labs, and the contamination first identified in Hennepin County has now been found in labs around the world.

"The knowledge and expertise that these forensic scientists bring to Hennepin County and the criminal justice system, at large, is invaluable," Hennepin County Sheriff Dawanna Witt said in a statement.

The lab is using a replacement product, and after completing testing on that product, "the lab is now able to resume DNA testing and analysis," the release said.

Ginny Barron, who runs the Barron Law Office and reviews DNA cases for the Hennepin County Public Defender's Office, said the crime lab went "above and beyond" in terms of communication.

Aaron Lavinsky, The Minnesota Star Tribune
Hennepin County forensic science supervisor and DNA technical leader Allison King handles a sample of the kind of plate formerly used by the crime lab, which was found to be contaminated.

"They have been completely transparent," she said,

There still will be next steps for defense attorneys. Barron said the crime lab will supply a corrective action that includes lists of all open or closed cases that have been affected by the contamination — a list that will extend beyond the fewer than 10 cases the lab has identified as needing retesting.

"If those cases are open we can litigate where appropriate," Barron said. "If they're closed we would have to look at what, if any, post-conviction actions there would be if that's appropriate."

In November, the Hennepin County Board approved a $223,000 contract with the Life Technologies Corp. for new DNA testing equipment and materials for the crime lab. Capt. Steve Labatt, director of the lab, said they had cut ties with the previous vendor that had provided the contaminated plates used in DNA extraction.

About half of the contract with Life Technologies will pay for validating new instruments from the vendor being installed in the lab. Labatt said the FBI requires all forensic labs to undergo extensive testing of new equipment before it can be used on case work.

"New instruments are not plug and play," he told commissioners on Nov. 12. "The validations have to be reproducible."

Labatt praised the Minnesota Bureau of Criminal Apprehension for stepping up to help with forensic work while the lab in Minneapolis was down. He said the agency's help minimized the backlog of DNA testing so cases would not be affected.

The contamination first came to the attention of attorneys when Labatt sent an email on Sept. 26 alerting the Hennepin County Attorney's Office that DNA personnel at the lab had discovered sporadic DNA contamination in their casework, likely originating "from an external product we use in the DNA testing process."

In October, Senior Hennepin County Attorney Dan Allard shared a memo with defense attorneys that said the latest update from the crime lab showed the contamination appears at random in casework but matches an unknown male's DNA profile from a discharged shell casing from 2022. The lab recognized the contamination when that DNA profile showed up as a "reagent blank" or negative control that is meant to highlight contamination.

"There will be months, or even a year or more, where it didn't show up and then would appear a number of times in a short period of time," Allard wrote.

Staff writer Christopher Magan contributed to this story.