Hennepin County Sheriff’s Office stops all DNA analysis after crime lab contamination

The Hennepin County Sheriff’s Office has paused all DNA casework while it investigates contamination in its crime lab, according to documents obtained by the Star Tribune. The investigation is ongoing and has identified approximately 75 samples that have been impacted.

Laboratory Director Capt. Steve 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.”

A memo from Senior Hennepin County Attorney Dan Allard on Monday that was shared with defense attorneys said the latest update from the crime lab shows 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 while noting that the crime lab has examined all of its data from 2016 through 2024 to identify the contamination in any casework.

He added that several other accredited forensic labs across the country have found this profile in their lab. The 75 contaminated samples that the Hennepin County Sheriff’s Office has identified are “impacted in part by the inability to rule out the presence of the contaminating profile rather than the clear presence of the contaminating profile.”

The next step in the process could include retesting the sample. The Hennepin County Attorney’s Office does not know which cases have been impacted and therefore doesn’t know how many are active investigations. In a statement the Attorney’s Office said it is taking the issue “extremely seriously” and “working continuously to identify any affected cases” while collaborating with the crime lab.

The Sheriff’s Office said in a statement it is “diligently investigating” the origin and extent of the contamination. The statement pointed out that the 75 known contaminated samples — a number the Sheriff’s Office acknowledges could change — is out of at least 50,000 samples tested from 2016 through 2024. It also says that because the contamination came from an unknown DNA profile “no criminal charges or convictions could have resulted” from it.

Hennepin County Chief Public Defender Mike Berger said in a statement that “the transparency afforded by the Sheriff’s Office is an important first step, and we are prepared to litigate all issues in all effected cases as they arise.”

When Labatt first emailed the Hennepin County Attorney’s Office about the contamination on Sept. 26, he noted fewer than 10 cases were impacted. But the lab needed to work back to see if there was other contamination, forcing it to pause all DNA casework.

One day later, on Sept. 27, Hennepin County Managing Attorney Michael Radmer sent an email to defense attorneys to disclose the leak and that the crime lab would be preparing a list of impacted cases.

Allard sent an update on Sept. 30 after speaking with Allison Dolenc, the DNA section supervisor at the sheriff’s crime lab.

That memo included the following information:

The crime lab noticed the contamination two weeks before the initial email from Labatt. The lab immediately stopped all work on those cases, but hadn’t released any findings related to contamination on those cases. The crime lab then started looking for other cases that may have been impacted by contamination — the first cases to be found with contamination were in 2022 and the lab was looking back to 2016. At the time of that email, the sheriff’s office was looking at cases in 2018. Dolenc told Allard the contamination “likely came from plasticware” used in DNA testing.

There was an update two days later that the crime lab had identified 12 impacted cases, two of which were active.

There are three other crime labs in the state that can process DNA evidence and “forensic serology,” or analysis of bodily fluids like blood, semen, saliva and urine: the Minnesota Bureau of Criminal Apprehension labs in St. Paul and Bemidji and the Tri County Regional Forensic Laboratory in Andover.

The Hennepin County Sheriff’s Office crime lab works with 35 law enforcement agencies in Hennepin County along with the State Patrol and federal law enforcement agencies. The Minneapolis Police Department works with the BCA crime lab; its contract this year was for $1.32 million.