A New Jersey man pleaded guilty Wednesday to killing his mother just two days after completing a 30-year prison sentence for the murder of a neighbor, reports CBS New York.

Steven Pratt pleaded guilty to manslaughter for killing his 64-year-old mother, Gwendolyn Pratt, in their Atlantic City home in October 2014. An autopsy revealed she died from massive blunt-force head injuries.

Pratt was 15 years old when he shot and killed his next-door neighbor Michael Anderson in an apartment building in 1984. He was tried as an adult and convicted of murder in 1986.

According to court records, Pratt and Anderson argued after Pratt and some of his friends refused to leave an apartment hallway where they were noisily hanging out. Pratt went back to Anderson's apartment with a lead pipe, but Anderson took the pipe away from Pratt and bloodied his face, the records show.

Pratt then returned with a borrowed handgun and shot Anderson in the face and shoulder, the court records show. Anderson, who Pratt said acted like a father to him, died days after the shooting.

Pratt was in tears Wednesday as he told a judge that he was guilty of killing his mother and didn't want a trial.

Pratt, 47, must serve 85 percent of a 25-year prison sentence before he'll be eligible for parole.