A convicted murderer beat his mother to death during an argument, just two days after he was released from prison, authorities said.

Gwendolyn Pratt, 64, was found dead around 6:30 a.m. Sunday at a home in Atlantic City, The Press of Atlantic City reported. An autopsy determined she died from massive blunt injuries to the head, Atlantic County prosecutor Jim McClain said in a statement.

Her 45-year-old son, Steven Pratt, was detained at the scene and charged with murder. He was being held on $1 million bail, and it was not known if he has retained an attorney.

A neighbor of the victim told the newspaper that the Pratt family had just thrown a welcome-home party for Steven. The neighbor, Ruan Tilghman-Pugh, said Steven had asked a cousin whether he could stay with him after having a disagreement with an aunt with whom he was staying over the weekend.

"It's so devastating," Tilghman-Pugh told the paper. "You just never know what people are going through."

Pratt was 15 when he shot and killed his next-door neighbor, Michael Anderson, in 1984. He was tried as an adult and convicted of first-degree murder in 1986. He received a 30-year prison sentence and was freed on Friday.

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 returned to Anderson's apartment with a lead pipe, but Anderson took the weapon away and bloodied Pratt's face.

Pratt then returned with a borrowed handgun and shot Anderson.