Robert Alioto, 48, of Petaluma, faces felony charges of conspiracy, possession of marijuana, transportation of drugs for sale, and furnishing or selling merchandise in prison, San Quentin spokesman Lt. Sam Robinson said.
He has posted bail and been released from Marin County Jail.
Alioto was not a prison guard, Robinson said. He was a materials store supervisor whose job entailed receiving merchandise from vendors, and he had been employed there since June 7, 2010, Robinson said.
Robinson said anyone who commits a crime in the prison, whether as an employee or inmate, will be prosecuted.
The investigation is continuing, Robinson said.