A man breaking into his ex-girlfriend’s apartment in Oakville was shot and killed Monday by a neighbor, who has not been charged with a crime. The shooting happened at an apartment complex in the 2800 block of Blackforest Drive.

Police said that the man who fired the gun heard his neighbor’s apartment door being forced in and a woman inside screaming for help just before 2:09 a.m. Monday, May 31. The neighbor armed himself and “responded to the woman’s aid,” police said.

According to the police account, the neighbor fired the gun, hitting the man breaking in, who was the woman’s ex-boyfriend.

Police identified the man who died in the shooting as Alex Mitchell, 27, of the 5200 block of Wind Rose Drive in Imperial.

Officers from the St. Louis County Police Department’s South County Precinct received a call reporting a burglary in progress at 2:09 a.m. When police arrived, officers took lifesaving measures for Mitchell. He was then taken to a local hospital, where he was pronounced dead.

The neighbor is cooperating with detectives and has not been charged with a crime.

The Bureau of Crimes Against Persons is investigating the shooting.