DETROIT (AP) — The parents of a teenager charged with killing four fellow students at a Michigan school knew that he was depressed, fascinated with guns and had tortured animals, even keeping a bird’s head in a jar, prosecutors said Thursday.

The court filing was in opposition to an effort by James and Jennifer Crumbley to get out of jail on a lower bond. They’re charged with involuntary manslaughter in the Oxford High School shooting under a theory that they had chances to prevent the bloodshed and made a gun available to their son.

The Crumbleys “will flee if they get the opportunity,” the Oakland County prosecutor’s office said, noting that the couple was behind in mortgage payments and put their house up for sale.

Ethan Crumbley, 15, is charged as an adult with murder and other crimes in the Nov. 30 shooting, which killed four students and injured seven other people.

The parents “willfully ignored the needs and well-being of their son and the threat he posed to others,” prosecutors said. “Their son was torturing animals, even leaving a baby bird’s head in a jar on his bedroom floor, which he later took and placed in a school bathroom.”

Ethan’s only friend had moved away at the end of October, the family dog had died and the teen was “sending his mother disturbing texts about his state of mind,” prosecutors said.

On the day of the shooting, the parents were summoned to discuss Ethan’s disturbing drawings spotted by a teacher on what appears to be a geometry worksheet.

It included a handgun and the words, “The thoughts won’t stop. Help me.” There’s a bullet with the phrase “blood everywhere” above a person who appears to have been shot. The paper also says “my life is useless” and “the world is dead.”

Ethan subsequently scratched out some of the images and words and wrote, “OHS Rocks! … I love my life so much!!!! … Were (sic) all friends here.”

School officials said the Crumbleys refused to take Ethan home, and the shooting followed. The prosecutor’s office earlier had described the writings but publicly attached them to a court filing for the first time Thursday.

“What is novel about this case is that defendants were made aware, in graphic form, of the serious risk posed by their son prior to the shooting. … These parents could have done something,” the prosecutor’s office said.

The Crumbleys, in custody since Dec. 4, are trying to get their bond reduced to $100,000 from $500,000. They were arrested in an art studio in Detroit, though their attorneys insist they weren’t trying to flee. The next court hearing is Jan. 7.

In a filing Wednesday, lawyers for the Crumbleys said they were devastated by the school shooting and didn’t know Ethan would commit violence that day.