Deborah Madden pleaded not guilty Monday to a felony cocaine possession charge in San Mateo County Superior Court.

The case is due back in court May 18.

The 60-year old Madden was arrested on March 3 after authorities investigating the disappearance of drugs at the San Francisco police lab found one-tenth of a gram of cocaine and a gun at her San Mateo home.

She remains free on $10,000 bail.

Madden has not been charged in the drug lab probe.