Northern California crime lab botches drug testing

Prosecutors in a Northern California county say human error led to six false positive drug tests at its crime lab.

The Santa Clara County District Attorney’s Office said Monday that a crime lab technician used the wrong chemical to conduct preliminary methamphetamine testing on the blood samples of 2,500 people arrested on suspicion of being under the influence of a controlled substance.

The testing occurred between January and March. Another technician discovered the error last month.

Prosecutors say retesting found six false positives, though none of those people is in custody because of the mistaken tests. Prosecutors plan to make changes at the drug lab, including labeling chemicals more clearly.

Assistant District Attorney David Angel said Tuesday that the technician who made the mistake has been reassigned pending an investigation.