A gun that mysteriously disappeared from a Queens police station on Saturday was sold back to cops in Brooklyn for $100, the Post has learned.

It was one of two guns swiped from lockers in a lieutenant’s office at the 103rd Precinct in Jamaica.

Investigators discovered an ex-con’s fingerprints on one of the lockers and the former jailbird is the prime suspect in the theft, according to sources.

The seller later walked into another stationhouse and sold back the .9mm weapon, which belonged to Lt. Charles Minch, the sources said.

Cops were searching for the suspect last night and were trying to figure out how he managed to get into a secure area, the source said.

The NYPD’s Internal Affairs Bureau is involved in the probe because police are also looking into the possibility the weapons were taken by a disgruntled cop.

IAB officers were searching officers’ lockers at the 103rd until the fingerprints were discovered.