A 26-year-old Brooklyn Park man was charged with murder Tuesday after authorities said he shot his alleged victim in the back last week during a quarrel that started in a south Minneapolis apartment building.

A witness told police that her former boyfriend showed up at her apartment in the Phillips West neighborhood on June 30 and got into an argument with the suspect, DaQuan Bradley, and another man, according to a criminal complaint filed in Hennepin County district court.

Authorities said Bradley shot Mario McGee, 27, in the back, from the window of the apartment as McGee was fleeing the building.

Neighbors reported hearing a man say he was going to shoot someone moments before the gunfire rang out, the complaint said.

Police found a single 9-millimeter shell casing in the grass below the bedroom window.

According to charges, an unidentified woman was in her south Minneapolis apartment shortly after 8 a.m. along with Bradley and several other people, when her ex-boyfriend, McGee, arrived. A fight soon began between Bradley and another man against McGee. Bradley and the other man forced McGee into the hallway, where they beat him until he escaped from the back door of the building.

A witness said that Bradley then went into woman's bedroom with her and seconds later, the witness heard a gunshot and the woman yell, "Oh my God, you just shot him." Other witnesses told police they saw McGee running from the apartment building when he was struck by the bullet and collapsed at 24th Street E. and Oakland Avenue S. Others reported hearing a window opening before the shot was fired.

Authorities said that when Bradley, who has several previous criminal convictions that prohibited him from carrying weapons, was arrested at his Brooklyn Park home, he had a 9mm handgun tucked into his waistband.

He has been charged with second-degree murder and is being held on $1 million bond. He is expected to make his initial court appearance on Wednesday.

McGee was among four people shot and killed over a bloody seven-day stretch that started with the June 27 slaying of a young mother who was gunned down while sitting in a car in the ­Willard-Hay neighborhood.

Libor Jany • 612-673-4064 Twitter:@StribJany