Jennifer Crumbley became the first parent in the United States to be found guilty of involuntary manslaughter on Tuesday for a mass school shooting committed by her teenage son.

Crumbley, 45, was convicted of four counts of involuntary manslaughter for her role in the Nov. 30, 2021, shooting in which her son, Ethan, opened fire at Oxford High School in Michigan, killing four of his classmates and injuring seven others. Involuntary manslaughter carries a maximum sentence of 15 years in prison, and Crumbley is set to be sentenced in April.

Prosecutors argued Jennifer Crumbley knew her son – 15 at the time of the shooting – was struggling with alarming mental health issues. They said instead of getting him the help he needed, she and her husband, James, bought their son the gun used in the attack and attempted to flee when it was becoming likely they would be charged. James Crumbley, who faces the same charges as his wife, is scheduled to go on trial in March.

Jennifer Crumbley, who took the stand in her own defense last week, said she never foresaw her son's deadly actions. She said her son did not show signs of being mentally ill other than being anxious about school and his future after graduation. She also said that while she and her husband bought their son the firearm, he was only allowed to use it at the shooting range with his dad. She said it was her husband's responsibility to securely store the gun.

She faced forward and kept her eyes closed as the jury delivered its verdicts. Craig Shilling, whose son Justin was killed in the shooting, looked on stoically as the verdict was read. Two people touched his back. Jennifer Crumbley then bowed her head and kept her eyes downcast as she walked, handcuffed, past a bank of cameras.

Oakland County Prosecutor Karen McDonald hugged relatives of the victims, including Shilling.

“I feel most of all that the cries have been heard, and I feel that this verdict is going to echo throughout every household in the country,” Shilling said, adding that accountability is something parents have been asking for, but the verdict is just one step in that process.

“We all have work now. We all know that we are to be held responsible for anything that we do,” he said.

Guilty verdict could impact views on gun safety

The groundbreaking trial is likely to impact how society views parents' responsibility when their children access guns and use them in mass shootings, legal experts said.

“This is a case that could create real incentives for parents to be much more cautious giving their children access to firearms," Adam Winkler, of the UCLA School of Law, previously told USA TODAY.

During closing arguments, Jennifer Crumbley's lawyer Shannon Smith said the case could set a dangerous precedent for parents who are trying to do their best for their children.

"I do wish, more than anything, that this case could bring justice to victims of the shooting, and to the victims of the terrorism that day," Smith said. "This is not justice. This is not how justice works. This does nothing for people who have lost everything … and it does nothing to (undo) the tragedy that unfolded on Nov. 30."

The shooter, now 17, was sentenced to life without parole in December after pleading guilty to multiple charges for the shooting that killed Madisyn Baldwin, 17; Tate Myre, 16; Hana St. Juliana, 14; and Justin Shilling, 17.

“Today’s verdict underscores the important responsibility of parents and gun owners in preventing children from having unsupervised access to deadly weapons," Nick Suplina, senior vice president for law and policy at Everytown for Gun Safety, said in a statement.

"Plain and simple, the deadly shooting at Oxford High School in 2021 should have — and could have — been prevented had the Crumbleys not acquired a gun for their 15-year-old son. This decision is an important step forward in ensuring accountability and, hopefully, preventing future tragedies."

Defense, prosecution argued over foreseeability

The seven-day trial largely focused on the foreseeability of the shooter's deadly actions and whether Jennifer Crumbley could have prevented it.

The prosecution cited a handful of text messages sent eight months before the shooting in which the teenager texted his mom that he saw a "demon" in their house and that clothes were flying around. He also texted a friend that he had "paranoia" and was hearing voices. The prosecution cited a journal the shooter kept, in which he wrote: "I have zero HELP for my mental problems and it's causing me to shoot up" the school.

Jennifer Crumbley testified she never saw the texts her son sent his friend; she never saw her son's journal; and that her son never asked her to take him to a therapist. If he had, she said she would have gotten him an appointment. She also testified that she didn't think it was relevant to notify the school that her son had access to a gun at home, saying she never thought her son would harm others as he had never been in trouble before.

On the morning of the shooting, the Crumbleys were summoned to the school over a troubling drawing their son had made on a math worksheet featuring a gun, a bleeding human body and the words, "The thoughts won't stop. Help me."

School officials told the parents their son was having a hard time and needed to be seen immediately by a mental health professional. Counselors at the school testified in Jennifer Crumbley's trial that because they were unaware that the teen might have access to a gun, they allowed him to stay at school that day, concluding that it would be better for him to be around peers than be alone at home. According to court testimony, the Crumbleys were never asked whether their son had access to a gun nor did school administrators search his backpack – where the teen kept the firearm – because they felt they had no probable cause to do so.

The parents returned to their jobs and promised to get their son counseling within 48 hours. Two hours later, their son fired his first shot.

Jennifer Crumbley testified that she and her husband did not bring him home because they were following the advice of the school officials who, she said, told her her son would be better off in class with peers rather than home alone.

CRUMBLEY TRIAL:Case could set precedent for how parents' responsibility is viewed

In closing arguments, defense attorney Shannon Smith told jurors “no one could have expected this, including Mrs. Crumbley."

But Oakland County Prosecutor Karen McDonald urged jurors to remember that Jennifer Crumbley said she "wouldn't do one thing different."

“The tragic part about it is none of it was hard. None of it,” McDonald said. "The smallest thing, just the smallest thing, could have saved Hana and Tate and Justin and Madisyn.”

Contributing: Ryan W. Miller, Celina Tebor, Christine Fernando, USA TODAY