Deborah Jean Madden, the ex-San Francisco criminalist who admitted to skimming cocaine from The City’s crime-lab evidence room, pleaded no contest Thursday to an unrelated drug charge in San Mateo County.

In March, police investigating last year’s crime-lab theft case say they found 0.09 grams of cocaine during a search of Madden’s San Mateo home.

Since she has no prior convictions, Madden likely won’t serve any time in jail for the drug possession. Under California law, she is eligible to enroll in rehab, San Mateo County District Attorney Steve Wagstaffe said Friday.

Madden was not prosecuted after she admitted to skimming cocaine from the evidence room.

The crime lab scandal led to the closure of the lab’s drug testing unit in early 2010 and the dismissal of about 700 cases by prosecutors.

maldax@sfexaminer.com