Jennifer Crumbley, the Michigan woman charged in connection with her son’s deadly school shooting rampage in 2021, was convicted Tuesday of involuntary manslaughter in the unprecedented case.

The unanimous verdict came on the second day of jury deliberations in a landmark trial in which Crumbley became the first parent to be held criminally responsible for a mass shooting committed by their child.

Crumbley, 45, was convicted on all four counts of involuntary manslaughter — one for each of the victims in the attack at Oxford High School in November 2021 — that she faced.

Her son, Ethan, now 17, pleaded guilty as an adult to murder, terrorism and other crimes and was sentenced in December to life in prison without parole.

Now, she faces up to 15 years in prison per count and remains held on bond. She will be sentenced April 9.

“It was very difficult,” a member of the jury said after the verdict. “Lives hung in the balance, and we took that very seriously.”

The juror said the decision hinged in large part on who was the last adult to handle the weapon.

“The thing that really hammered it home was that she was the last adult with the gun,” the juror said.

Craig Shilling, the father of Justin Shilling, 17, one of the four victims in the school shooting, teared up when the verdict was announced. He later hugged Oakland County prosecutor Karen McDonald and members of her team and shook the hands of law enforcement officers who testified.

“We have been asking for accountability across the board, and this is one step towards that,” Shilling said outside the courtroom. “I feel that moving forward is not going to be any easier because of what we left behind, but it gives us hope for a brighter future.”

The trial, which opened Jan. 25 in an Oakland County courtroom, hit at themes of good parenting and gun safety, and it has come at a consequential moment in the U.S. when a drumbeat of school shootings have roiled communities like Uvalde, Texas; Nashville, Tennessee; and Perry, Iowa.

In an effort to determine to what extent a parent should be held accountable for the actions of their child, jurors in Oakland County examined more than 400 pieces of evidence, including text messages and photos from Crumbley’s cellphone, and dramatic video of the shooting spree, which left many in the courtroom visibly shaken.

The prosecution called more than 20 witnesses, including law enforcement officials and school staff members, while the defense brought in just one: the defendant.

To prove its case, the prosecution tried to portray Crumbley as a neglectful mother who cared more about her hobbies and carrying on an extramarital affair than about spending time with her son. Then, when she and her husband gave their son a semi-automatic handgun as a gift in the days before the shooting, prosecutors said, neither of them properly stored it.

On the day of the shooting, after the Crumbleys had been summoned to the school because of a disturbing drawing of a gun made by their son, the parents didn’t tell school officials he had access to a weapon or take him home.

Ethan Crumbly would go on to kill four students: Justin Shilling; Madisyn Baldwin, 17; Tate Myre, 16; and Hana St. Juliana, 14.

Crumbley’s defense lawyer, Shannon Smith, suggested that it was James Crumbley who was specifically in charge of storing the weapon and that the school knew Ethan was having trouble paying attention in classes but didn’t fully inform Jennifer Crumbley.

Smith had asked the jury in her closing argument to acquit her client, “not just for Jennifer Crumbley, but for every mother who’s out there doing the best they can, who could easily be in her shoes.”

James Crumbley, 47, is expected to stand trial next month on the same involuntary manslaughter charges. The judge in Crumbley’s trial imposed a gag order that prevents the prosecution and the defense from speaking publicly until after his trial.

Jennifer Crumbley took the stand in her own defense. She testified that her son was generally worried about his future after high school and was “depressed” but that his mental health never alarmed her enough that she felt he needed to see a professional.

She acknowledged that she could have taken him home on the day of the shooting but said she also didn’t believe he was capable of committing such violence. More than two years after the shooting, she told the jury she “wouldn’t have” done anything differently.

“I don’t think I’m a failure as a parent,” she said.

Craig Shilling said the jury’s decision shows how important it is for parents to be mindful of their children’s needs.

“Do your due diligence with your child,” he said. “You cannot choose to take your own interest over your child, especially when it comes to mental health.”

Gun safety groups echoed that the verdict is a warning that parents can be held responsible.

“Plain and simple, the deadly shooting at Oxford High School in 2021 should have — and could have — been prevented had the Crumbley’s not acquired a gun for their 15-year-old son,” Nick Suplina, senior vice president for law and policy at Everytown for Gun Safety, said in a statement. “This decision is an important step forward in ensuring accountability and, hopefully, preventing future tragedies.”