BEND, OR -- Deschutes County District Attorney John Hummel continues to review cases involving Bend's Oregon State Police Crime Lab. Lab analyst Nika Larsen is currently under investigation for allegedly tampering with drug evidence. 

D.A. Hummel told the League of Women Voters Thursday, he's about a third of the way through the review. "There are 1100 cases that I'm going through, looking through every single case. I've gotten through now about 300 and I think about nine of them I've determined the conviction will be overturned."

He says there are several factors to consider during each review. "If she was directly involved and we have 15 other pieces of evidence showing guilt, I say 'hold it.' But, if she's directly involved and we have no other evidence of guilt, I don't have confidence in the conviction. So, that happened nine times. By August, I'll get through those all, and I'll announce the final numbers to the public."

The investigation into Larsen's work at the lab began last fall.