PONTIAC, Mich. — A Michigan jury received instructions from a judge and began deliberations Monday in a novel trial against a school shooter’s mother who could go to prison if convicted of involuntary manslaughter in the deaths of four students in 2021.

“You must not let sympathy, bias or prejudice influence your decision,” Oakland County Judge Cheryl Matthews said.

Prosecutors say Jennifer Crumbley was grossly negligent when she failed to tell Oxford High School officials that the family had guns, including a 9 mm handgun that her son, Ethan Crumbley, had used at a shooting range just a few days earlier.

The school was concerned about a macabre drawing of a gun, bullet and wounded man, accompanied by desperate phrases, on the boy’s math assignment. But he was allowed to stay in school on Nov. 30, 2021, following a roughly 12-minute meeting with Jennifer and James Crumbley, who didn’t take him home.

The teenager pulled the gun from his backpack in the afternoon and shot 10 students and a teacher, killing four peers. No one had checked the backpack.

“He literally drew a picture of what he was going to do. It says, ‘Help me,’ ” prosecutor Karen McDonald said during closing arguments Friday in suburban Detroit.

Jennifer Crumbley knew the gun in the drawing was identical to the new one at home, McDonald said.

“She knew it wasn’t stored properly,” the prosecutor added. “She knew that he was proficient with the gun. She knew he had access to ammunition.”

“Just the smallest steps” by Jennifer Crumbley could have saved the lives of Hana St. Juliana, Tate Myre, Justin Shilling and Madisyn Baldwin, the prosecutor said.

About four hours into deliberations Monday, the jury sent a note to the judge asking if it could “infer anything” from prosecutors not presenting Ethan Crumbley or others to explain specifically how he got the gun from home.

“The answer is no. You’re only allowed to consider the evidence that was admitted in the case,” Matthews told jurors.

The shooter, now 17, pleaded guilty to murder and terrorism and is serving a life sentence. His mother wanted to call him as a defense witness during the trial, but his lawyers said he would invoke his right to remain silent. He still might appeal his sentence.

During her closing argument last week, defense attorney Shannon Smith told jurors that a conviction would have a chilling effect on unwitting parents whose kids break the law. The tragedy, she argued, was not foreseeable.

Ethan Crumbley was a “skilled manipulator” who didn’t have mental illness, and the gun was the responsibility of James Crumbley, not his wife, Smith said.

“Unfortunately this is a case where the prosecution made a charging decision way too fast,” Smith said. “It was motivated by obvious reasons, for political gain and done for media attention.”

She said the case won’t bring justice to the victims or their families: “It certainly doesn’t bring back any lives.”

The jury of six men and six women includes some gun owners or people who grew up with firearms in their house. They said it wouldn’t interfere with their ability to be fair.

Jennifer Crumbley, 45, and James Crumbley, 47, are the first parents in the U.S. to be charged in a mass school shooting committed by their child. The latter faces trial in March.

Besides knowledge of the gun, the Crumbleys are accused of ignoring their son’s mental health needs. In a journal found by police in his backpack, he wrote that they wouldn’t listen to his pleas for help.

“I have zero help for my mental problems and it’s causing me to shoot up the ... school,” Ethan wrote.

The maximum penalty for involuntary manslaughter is 15 years in prison. The Crumbleys have been in jail for more than two years, unable to post $500,000 bond while awaiting trial.