SAN FRANCISCO—A spokesman for the U.S. Attorney's Office says a mistrial has been declared in the federal trial of a former San Francisco Police Department's crime lab technician accused of skimming cocaine from the lab.

Spokesman Jack Gillund says U.S. District Judge Susan Illston declared the mistrial Wednesday in the case against Deborah Madden when jurors said they were unable to reach a unanimous verdict on charges of obtaining cocaine by fraud, deception or subterfuge.

Madden was at the center of a scandal that resulted in hundreds of drug cases being dropped after she was accused of taking cocaine evidence from the lab while she worked there in late 2009.

The federal charges came after state prosecutors declined to file charges.

The 62-year-old Madden, a resident of San Mateo, later pleaded no contest in a San Mateo County court to possession of cocaine.