PONTIAC, Mich. — Prosecutors sought to pick apart Jennifer Crumbley’s self-description as a “vigilant parent and helicopter mom” when she returned to the stand Friday, instead suggesting the mother of school shooter Ethan Crumbley was too consumed with her hobbies, such as her horses, and an extramarital affair to notice her son’s deteriorating mental state.

And on the day of the shooting at Oxford High School in 2021, when Crumbley and her husband, James, met earlier with school officials about a disturbing drawing of a gun found by their son’s teacher, prosecutors noted that she again chose not to be with her son by not taking him home.

“On November the 30th of 2021 at 12:51 p.m., you could have been with him?” Assistant Oakland County Prosecutor Marc Keast asked Crumbley during his cross-examination.

“I could have, yes,” Crumbley said.

“And you didn’t?” Keast asked.

“Nope,” she replied.

That fateful decision to leave her then-15-year-old son at school, where he would go on to fatally shoot four students and injure several others that afternoon, is part of a pattern of choices that prosecutors believe builds a case alleging Crumbley was unlawfully negligent.

The unprecedented trial has turned on an unusual charge of holding a parent of a school shooter criminally responsible for their child’s actions. The jury must decide if Crumbley, 45, is guilty of involuntary manslaughter in the deaths of the four students by either failing to store the firearm in a way that would have obstructed her son from gaining access to the gun and ammunition or failing to exercise “reasonable care” of her son and prevent him from carrying out the mass shooting.

During its cross-examination, the prosecution hammered on the idea that Crumbley was aware of warning signs that Ethan was troubled, “depressed” and “acting sad,” particularly when a best friend moved away, and yet she never thought to seek the help of a mental health professional in the months before the shooting.

And they questioned her about her previous testimony in which she said it was her husband who bought him the semi-automatic handgun, and that while she took her son to a gun range the weekend before the mass shooting, she left the storage of the weapon to her husband.

That “was his thing,” she testified Thursday.

Keast said that while she may have “entrusted” the responsibility of storing the gun to her husband, it was “pretty clear you didn’t trust James with much,” noting that she had issues with him holding down a job, handling his money and even getting out of bed on time.

James Crumbley, 47, is expected to stand trial next month on the same involuntary manslaughter charges.

Even after Jennifer and James Crumbley were arrested on those charges after law enforcement found them holed up in an art studio in Detroit, prosecutors suggested she still didn’t have concern for her son, who was immediately held following the shooting.

Prosecutors played her phone calls from the Oakland County Jail in which she asked her father to set up a GoFundMe to pay for the boarding of her horses and to Google how many calories are in bologna sandwich and other food.

Keast questioned why she didn’t mention her son in any jail phone calls for the first 10 days of her arrest. She responded that she didn’t think she could.

Emotions have run high throughout the trial, as jurors heard from survivors of the shooting and watched video of the massacre from inside the high school. Crumbley, too, has sobbed repeatedly from her seat.

The jury on Thursday heard excerpts from Ethan Crumbley’s journals in which he wrote, “My parents won’t listen to me about help or a therapist,” expressed his desire to “shoot up” his school and said he was going to get a 9 mm pistol.

The prosecution hit back on Friday that she was preoccupied with her pursuits, including maintaining an affair that included meeting at a Costco parking lot once a week and even arranging a meetup on AdultFriendFinder, an app for sexual encounters.

“And that took your time and energy and focus?” Keast asked.

“I don’t believe it took that much time, no,” Crumbley said.

On Thursday, when asked about her parenting by her defense lawyer, Crumbley testified, “I don’t think I’m a failure as a parent,” but was remorseful about her son’s actions.

Ethan Crumbley’s rampage led to four deaths: Madisyn Baldwin, 17; Tate Myre, 16; Hana St. Juliana, 14; and Justin Shilling, 17.

“I wish he would have killed us, instead,” Crumbley testified Thursday.

Closing arguments were expected Friday.

Seventeen people have been called as jurors, but only 12 will weigh Crumbley’s fate; no one in the court, including the jurors themselves, was being told who is among that final group until the deliberations begin.

The jury has not been sequestered during the trial but has been ordered to refrain from watching news reports, checking social media or speaking about the case.

Selina Guevara reported from Pontiac and Erik Ortiz from New York.

This article was originally published on NBCNews.com