Pontiac, Mich. (AP) -- An ex-convict working as a janitor at police headquarters pried open officers' lockers and stole four service pistols and ammunition, police said.

Walter Riley Monroe of Pontiac, was arraigned Thursday on multiple charges related to the thefts.

Monroe sued the same police department in 1992, alleging he had been beaten during an arrest. The suit was dropped after he refused to cooperate with his lawyer and later failed to show up in court to act as his own attorney.

Police recognized the 12-time felon when he took the job, but did not consider him a threat, Police Sgt. Terry Healy told the Detroit Free Press.

Monroe, who was on parole when he began the job, has a history of shoplifting, drug possession, breaking and entering, burglary and possession of stolen property.

He confessed this week to stealing the semi-automatic pistols during his daytime cleaning shifts and selling them, Healy said. At least two of the guns have been recovered, police said.

District Judge Christopher Brown entered innocent pleas for Monroe on all counts and set bond at $50,000. A court-appointed attorney requested by Monroe had not yet been chosen. If convicted, he faces up to 29 years in prison, plus additional time for violating parole.