The ex-boyfriend of a Rikers correction officer fatally shot in Brooklyn in early December was arrested in a separate incident involving another ex-girlfriend, a law enforcement source said.

Keon Richmond, 34, of East Flatbush, is accused of setting fire to a car owned by an ex-girlfriend in East New York on Oct. 23, police said. He was charged with criminal mischief, menacing and harassment on Wednesday, they said.

Richmond is also being questioned in the ongoing investigation of the shooting of Alastasia Bryan, 25, a Rikers correction officer, as she sat in her car in Flatlands on Dec. 5, a law enforcement source said. Bryan and Richmond had been in a relationship before the incident, the source said.

Video of the shooting shows a man in dark clothing walk up to Bryan’s parked car, fire multiple shots into the drivers side and run away.

Richmond has 31 priors, including charges of criminal possession of a weapon, reckless endangerment and burglary, a law enforcement source said.