Contaminant ‘potentially’ affects 75 samples in Hennepin County crime lab

Dozens of DNA samples in Hennepin County’s crime lab could have been contaminated by outside materials, the sheriff’s office said on Monday.

Staff at the Hennepin County Sheriff’s Office Forensic Science Laboratory encountered “sporadic DNA contamination in casework from an unknown source.” That contaminant — which came from an “external product” used in DNA testing — could have affected 75 of the county’s 50,000 samples in storage, but the exact number of impacted samples is still under investigation, the sheriff’s office said.

“We immediately halted all DNA analysis casework, and we are diligently investigating the origin and the impact of the contamination,” said Megan Larson, a public information officer with the Hennepin County Sheriff’s Office. “As an internationally accredited laboratory, we are working closely with our accreditation organization during this process.”

The sheriff’s office emphasized that the contamination is from an “unknown DNA profile,” so it couldn’t result in any wrongful criminal charges or convictions.