ST. PAUL, Minn. (AP) — St. Paul’s police chief has suspended drug testing at the department’s crime lab following reports of shoddy procedures.

The lab has lost its biggest customers, including the Minnesota State Patrol and Washington and Dakota counties, after they learned of problems at the lab. In a letter to Mayor Chris Coleman, Chief Thomas Smith says he plans to reorganize the leadership structure and “explore additional technical expertise.”

A nationally recognized forensics expert, Jay Siegel, testified during a hearing this week that the lab is doing “insufficient, unvalidated testing” by untrained analysts.

The St. Paul Pioneer Press (http://bit.ly/ObisOE ) says that in the past four years, prosecutors in Ramsey, Washington and Dakota counties have filed more than 3,600 cases, many using evidence analyzed at the lab.