Surpassing:Watch 'Crumbley Trials' trailer: New doc explores Michigan school shooter's parents cases

The Surpassingunprecedented trials of Michigan parents James and Jennifer Crumbley, which led to the country’s first involuntary manslaughter convictions for parents of a school shooter, are the focus of an hourlong documentary premiering April 18.

In “Sins of the Parents: The Crumbley Trials” (streaming on Hulu), ABC News Studios obtained exclusive access to Oakland County Prosecutor Karen McDonald and her team as they built their case against the parents of Ethan Crumbley, who at age 15 murdered four students — Tate Myre, 16; Hana St. Juliana, 14; Madisyn Baldwin, 17, and Justin Shilling, 17 — at Oxford High School on November 30, 2021. At the time of the shooting,

“You don’t get to walk away from that; you just don’t,” McDonald says in a trailer for the documentary, exclusively at USA TODAY.com.

The troubled shooter, who also injured seven others, was portrayed by his defense team during his trial as a lost and severely depressed teenager who was spiraling out of control in the months before the shooting, hallucinating and contemplating suicide and begging unsuccessfully for help, as he expressed in his journal and texts.

"I have fully mentally lost it after years of fighting my dark side. My parents won’t listen to me about help or a therapist," Ethan Crumbley wrote in his journal.

“He was crying for help and being ignored,” Ven Johnson, an attorney who represented victims and their families, says in the documentary preview.

“Those people are yikes,” McDonald says of the Crumbley parents. “The life they lived was just crazy.”

Also in the trailer, McDonald expresses concern about a text in that Jennifer Crumbley sent her son after learning he'd been researching bullets in class. "LOL I’m not mad," Crumbley texted. "You have to learn how to not get caught."

James and Jennifer Crumbley, parents of Michigan shooter, sentenced to 10 to 15 years in prison

His parents "do not seem shocked about him having the gun. There was no shock, zero,” says McDonald, who became visibly incensed at James Crumbley’s March trial, as she focused the jury's attention on perhaps the most damning piece of evidence in the case: a troubling drawing Ethan made on the morning before the shooting on his math worksheet. It features a gun, a human body bleeding and the words: "The thoughts won't stop. Help me."

The boy's parents were summoned to the school, though the Crumbleys returned to their jobs after they met with a counselor and dean of students, vowing to get their son help within 48 hours. The school officials concluded the student was no threat to himself or others and allowed him to return to class.

Two hours later, the boy fired his first shot. Had James Crumbley taken his son's drawing more seriously and taken the boy home, McDonald argued, the tragedy could have been avoided.

James Crumbley,father of Michigan school shooter, found guilty of involuntary manslaughter

Jennifer Crumbley verdict:After historic trial, jury finds mother of school shooter guilty

The Crumbleys were convicted on four counts of involuntary manslaughter and sentenced to 10 to 15 years Tuesday. Ethan has been sentenced to life in prison.

Before their sentencing, Judge Cheryl Matthews addressed both parents. "Mr. Crumbley, it's clear to this court that because of you, there was unfettered access to a gun or guns, as well as ammunition in your home.

"Mrs. Crumbley, you glorified the use and possession of these weapons," she added.

The victims' families have long argued that the Crumbleys aren't the only ones who made mistakes, that school officials also were negligent and must be held accountable for their children's tragic deaths.

"While we are grateful that James and Jennifer Crumbley were found guilty, we want to be very clear that this is just the beginning of our quest for justice and true accountability," the families of the four slain students said in a joint statement after the verdict came down. "There is so much more that needs to be done to ensure other families in Michigan and across the country don’t experience the pain that we feel and we will not stop until real change is made."

Contributing: Tresa Baldas, Gina Kaufman and Lily Altavena of the Detroit Free Press and Jeanine Santucci and Cybele Mayes-Osterman, USA TODAY