A woman who says she witnessed the 2012 shotgun killing of a man outside a Tigerland apartment told a jury Thursday that Mason Chiapuzio, who is standing trial on a second-degree murder charge, gave her a chilling confession a short time after the predawn slaying.

Jennifer Prine testified it was still dark when she and Chiapuzio’s mother, Tressie Newberry, drove back into Tigerland after seeing a man ambushed and shot to death. They went to Chiapuzio’s apartment, where the young man, now 22, met them at the door and pulled Prine into a side room to speak privately with her.

“He tried to explain to me why he did what he did,” said Prine, who a grand jury declined to indict in 2013 after she was booked on a murder count in the case. “He said sometimes the earth gets dirty, and God puts people on the earth to help clean it off.”

Prine, 30, said she and Newberry witnessed the killing of 29-year-old Brandon Harris, and that Newberry told her shortly after the murder that Harris had raped Newberry’s former girlfriend, who killed herself.

Prine testified she and Newberry had been in a “brief relationship” at the time of Harris’ death. Prine said she did not know Harris, but Newberry did know him.

The night Harris was killed, Prine said Newberry drove her to a house where they picked him up.

They then drove to Sharlo Avenue in Tigerland and parked outside some apartments where Chiapuzio lived.

Prine said she and Harris both got out of the car, and while Harris was introducing himself to her, a masked gunman emerged from the bushes with a shotgun and started firing.

Prine said she and Harris ran in different directions, but Prine reached a dead end, so she turned around and ran past the shooter just as he shot Harris in the head. Prine said Newberry did not run.

Newberry, 43, is serving a life prison term in the April 15, 2012 killing.

She was convicted of second-degree murder in September.

After the shooting, Prine said she ran to some railroad tracks and called Newberry, who picked her up and told her that Chiapuzio was the triggerman. Harris was shot three times, and his pockets were turned inside out.

“She told me I needed to keep calm, and that it was Mason who just shot Mr. Harris, and that I wouldn’t understand. I wasn’t supposed to be there,” Prine said.

An East Baton Rouge Parish jury will begin its deliberations Friday after prosecutor Will Morris and Chiapuzio’s attorney, Gail Ray, give their closing arguments to the panel, and state District Judge Beau Higginbotham instructs the jurors.

Morris rested the state’s case Thursday after Prine testified.

Chiapuzio did not testify in his own defense. Ray rested the defense’s case after calling several witnesses, including Chiapuzio’s father.