In 2021, Ethan Crumbley walked out of a toilet, pulled a gun from his backpack at school and killed four students.

Prosecutors said on Tuesday that Jennifer Crumbley was negligent when she failed to tell Oxford High School that the family owned guns, including a 9mm handgun that her son, Ethan, used at the November 30 attack.

Crumbley, 45, faced four counts of involuntary manslaughter, one for each of the victims. Her husband, James, 47, is set to face his trial next month.

Oakland County prosecutors argued during the trial that the mother, despite not pulling the trigger herself, negligently stored the gun and ammunition and, therefore, should be held criminally responsible for the deaths.

They said that she and her husband knew Ethan was mentally in a “downward spiral” and posed a danger to others but allowed him access to the fateful pistol.

They added that Crumbley had a duty under Michigan law to prevent her son, who was 15 at the time, from harming others.

But Shannon Smith, the lawyer for Crumbley, argued that she was not responsible for buying or storing the gun used by her son and that there were no warning signs that he would harm his classmates or to foresee a crime taking place.

Crumbley testified in her defence during the trial and said her husband was responsible for securely storing firearms at home and that her son had been anxious about getting into college.

During Smith’s closing arguments, she asked the jury, comprising six men and six women, including some gun owners, to find her client not guilty since her son’s crimes were “unforeseeable”.

“Can every parent really be responsible for everything that their children do?” Smith asked.

School shooting

On the morning of the school shooting, staff members who were concerned with Ethan’s drawing of a gun, bullet and wounded man next to the words “Blood everywhere,” “My life is useless,” and “The thoughts won’t stop – help me”, on his math assignment, met the Crumbleys.

According to prosecutors, Ethan’s parents were told that he needed counselling and they needed to take him home, but the couple resisted taking him and did not search his bag or ask about the gun.

However, Jennifer challenged that account, telling jurors they had mutually agreed that Ethan could remain in school that day and did not think he posed a danger to other students.

Hours later, Ethan walked out of a toilet, pulled a gun from his backpack and shot 10 students and a teacher, killing four students.

The gun used was a Sig Sauer 9mm that his father, James, had bought just four days earlier. Jennifer had also taken her son to a shooting range that weekend.

Ethan, now 17, pleaded guilty to murder and “terrorism” and is serving a life sentence.