(NewsNation) — Opening statements began Thursday in the trial for a Michigan woman who faces involuntary manslaughter charges in a school shooting committed by her teenage son.

Prosecutors insist Jennifer Crumbley, 45, bears some responsibility for the deaths of four students at Oxford High School in 2021.

“They weren’t in a car crash. They weren’t sick. They were murdered in an act of terror by the defendant’s son,” assistant prosecutor Marc Keast said during opening statements. “Jennifer Crumbley didn’t pull the trigger that day, but she is responsible for their deaths.”

Jennifer Crumbley and James Crumbley, are accused of failing to address then-15-year-old Ethan Crumbley’s mental health needs, and making a gun accessible to their son at home.

Shannon Smith, Jennifer Crumbley’s attorney, told jurors that her client knew very little about the family’s guns and it was James Crumbley who was responsible for storing the family’s guns secretly.

“Jennifer Crumbley didn’t know anything about guns. She went to the shooting range one time with James and the shooter,” Smith said.

The prosecution alleges the Crumbleys ignored their son’s pleas for help and refused to take him home on Nov. 30, 2021, the day of the shooting, despite the discovery of a troubling math sheet with drawings of guns, deceased victims, and distressing words.

Keast told jurors the Crumbleys were cold when they appeared at the school that morning.

“They didn’t say anything about the fact that that firearm (in the drawing) is identical to the 9 mm (they had bought him.) They didn’t mention anything about how the gun was stored … They didn’t embrace their son. They didn’t stop by the house to look for the gun. they never once asked their son, ‘Where’s the gun?'”

He added that’s why she’s responsible for these deaths, stressing multiple times: “She did nothing.”

He also said the shooter was in a downward spiral that had begun months before the shooting.

Smith said during the trial, Jennifer Crumbley would take the stand and share how her son had “not been in her son” and was manipulating her in the months before the shooting.

The Crumbleys are not accused of knowing their son’s plans. But prosecutors said they were grossly negligent. It’s the first time parents have been charged in a mass school shooting.

Jennifer and James Crumbley are being tried separately. James Crumbley’s trial will begin in March. Ethan Crumbley, now 17, was sentenced to life in prison in December after pleading guilty to murder, terrorism and other crimes.

Jury selection began for Jennifer’s trial Tuesday in Oakland County court, 40 miles north of Detroit. A jury was selected on Wednesday.

The judge and lawyers spoke to prospective jurors for hours, probing for any strong opinions about the tragedy, guns, parental responsibility and other themes that will emerge at trial.

Judge Cheryl Matthews said the case is “deeply sad” but that “sympathy” should have no role in determining guilt or innocence.

Defense attorneys insist that the Crumbleys could not have foreseen the murders.

Jill Soave, the mother of one of the four victims said the Crumbleys carry some of the blame.

“We may learn some more with these trials. But I feel that they are absolutely to blame. It’s three parts — it’s the shooter, it’s the parents, and it’s the school. Each of them should be held accountable to the fullest because we have four dead children. So yes, I do believe that they are in the right place, that they should be going to trial. And I don’t have much compassion for them. I just don’t,” Soave said.

On Tuesday, Ethan Crumbley’s lawyers stated they would encourage him not to testify if he is called as a witness at his parents’ trials. The State Appellate Defenders Office also confirmed to NewsNation that Ethan Crumbley is appealing his life-without-parole conviction.

The Crumbleys have been in jail for more than two years awaiting trial, unable to afford a $500,000 bond. Involuntary manslaughter in Michigan carries a maximum sentence of 15 years in prison.