A Rare Question for Michigan Jurors: Do a Son’s Crimes Merit His Mother’s Conviction?

In closing arguments at the trial against Jennifer Crumbley on Friday, lawyers for the prosecution and defense differed sharply over whether jurors should take the extraordinary step of holding a mother responsible for her child’s horrific crimes.

But both sides agreed on one point: This has been a singular trial.

Prosecutors are seeking to hold Ms. Crumbley partially responsible for the Nov. 30, 2021, shooting at Oxford High School in Michigan. Her son, Ethan Crumbley, who was 15 at the time, killed four classmates at the school and injured seven others, in the deadliest school shooting in the state.

“It’s a rare case,” said the Oakland County prosecutor, Karen D. McDonald, who accused Ms. Crumbley of negligence but acknowledged the high burden of proving beyond a reasonable doubt that she had committed a crime.

“It takes the unthinkable,” Ms. McDonald added. “And she has done the unthinkable, and because of that, four kids have died.”

Since last week, the jurors have heard wrenching statements from witnesses, combative debates between lawyers, and hours of testimony from Ms. Crumbley, 45. The charges against her and her husband, who each face four counts of involuntary manslaughter, are at the leading edge of a push by some prosecutors to hold parents accountable when they are suspected of enabling deadly violence by their children.

The husband, James Crumbley, 47, will be tried separately in March.

Ms. Crumbley’s lawyer, Shannon Smith, said that her client should not be punished for the bloodshed that her son set in motion, in part because Ms. Crumbley could not have foreseen what would happen. Ms. Smith also argued, using examples from her own life, that parenting could be a messy and unpredictable job.

“This case is a very dangerous one for parents out there,” she told the jurors on Friday. “It just is. And it is one of the first of its kind.”

Since Ms. Crumbley’s trial began last week, prosecutors in Oakland County have called 21 witnesses, including law enforcement officials, Ms. Crumbley’s friends and those who saw the shooting, to testify about the day of the rampage and the events leading up to it.

Ms. Smith participated in cross-examinations but called only one defense witness, Ms. Crumbley, who testified on Thursday that she had always tried to protect her son but did not expect him to hurt other people.

“I wish he would have killed us instead,” Ms. Crumbley said.

Throughout the trial, the defense tried to depict Ms. Crumbley as a “hypervigilant mother” who was anxious about her teenager’s whereabouts and attentive to the everyday details of his life, like bothersome braces, geometry grades and bowling practice.

“I am asking that you find Jennifer Crumbley not guilty,” Ms. Smith said on Friday. “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.”

But prosecutors have suggested that Ms. Crumbley paid more attention to her two horses, and her extramarital affair, than to her son’s needs, and that she ultimately missed glaring warning signs that he was on the verge of committing unspeakable violence.

This week, lawyers also sparred over who was to blame for the fact that Ethan Crumbley had not been sent home from school before the shooting, despite a violent drawing he made. The drawing included a gun and the phrase “blood everywhere,” prompting school officials to meet with his parents just hours before the attack.

“He drew her a picture,” Ms. McDonald said on Friday. “Pretty egregious and unique circumstances.”

Also introduced as evidence during the trial was months of communications between Ms. Crumbley and her son, including text messages from months before the shooting in which Ethan had told his mother that their home was haunted, possibly by a demon.

Ms. Crumbley, prosecutors pointed out, did not always respond.

But Ms. Crumbley said in her testimony on Thursday that Ethan and his parents had joked for years about whether their house was haunted. “He was always sarcastic,” she said. “Always messing around with us.”

On Thursday, a detective guided jurors through the pages of Ethan’s journal, which was found at the school after the shooting. He had written about a plan to cause bloodshed, adding drawings of guns and pleas for help regarding his mental health. “My parents won’t listen to me about help or a therapist,” he wrote.

But Ms. Crumbley said she had never seen the journal entries, nor heard her son ask for a therapist.

Prosecutors also spent time discussing Ethan’s access to the Sig Sauer pistol that he used in the shooting. The evidence indicates that Ethan’s father had purchased the gun as a Christmas present for the teenager.

While Ms. Crumbley accompanied Ethan to a shooting range a few days before the rampage, she testified on Thursday that her husband, who was more familiar with firearms, had been responsible for storing the gun. But prosecutors accused her on Friday of trying to distance herself from the weapon.

Ms. Smith had hoped to question Ethan. But the judge, Cheryl A. Matthews, said she would not require him to testify, because he was expected to invoke his Fifth Amendment right against self-incrimination. Though he pleaded guilty, Ethan’s life sentence without parole is still eligible for appeal.

Now, jurors in his mother’s trial will decide whether she is guilty of enabling his violence.

The judge told the jurors that she would give them their instructions when they returned to the courtroom on Monday morning to begin deliberations.