(NewsNation) — Michigan school shooter Ethan Crumbley could testify against his parents after pleading guilty to all charges, including terrorism and first degree murder.

Jennifer and James Crumbley are also facing trial for manslaughter, though parents of school shooters have rarely been charged with crimes.

The shooting at Oxford High School left four students dead and seven injured. The school has been accused of failing to protect students and ignoring warning signs that Crumbley could be a danger to his classmates.

The day before the shooting, a teacher had discovered a drawing with a gun pointing at the words: “The thoughts won’t stop. Help me.” There was an image of a bullet with the message: “Blood everywhere.” He was sent back to class after his parents refused to take him home.

Prosecutors allege the Crumbleys knew their son was showing signs of mental distress and failed to intervene.

Crumbley’s plea revealed more information about the gun his parents purchased for him.

Ethan Crumbley admitted under questioning Monday that his own money was used to purchase the gun, which his father bought for him on Nov. 26, a few days before the shooting. He also agreed that the gun was “not locked” in a container or safe the morning he took it to the school.

“It definitely helps the prosecution against the Crumbley parents,” said Dave Aronberg, state attorney for Palm Beach County, Florida. “This goes to their recklessness.”

Previously, a teacher had caught Ethan looking up ammunition on his phone. The school contacted Jennifer Crumbley, who told her son in a text message: “Lol. I’m not mad at you. You have to learn not to get caught,” the prosecutor’s office said.

Aronberg said it’s possible Crumbley, who is facing life in prison, could testify against his parents in hopes of a more lenient sentence, including the possibility of parole later on.

Watch the full interview in the video player above.

The Associated Press contributed to this report.