Jury finds Jennifer Crumbley guilty of involuntary manslaughter in son's school shooting

A jury has found Jennifer Crumbley, the mother of Michigan school shooter Ethan Crumbley, guilty of involuntary manslaughter in connection with the shooting deaths of four students at Oxford High School in November 2021.

Crumbley was found guilty of four counts of involuntary manslaughter in connection with the shooting, one for each victim: Madisyn Baldwin, 17; Tate Myre, 16; Justin Shilling, 17; and Hana St. Juliana, 14.

The jury deliberated for roughly 11 hours, beginning on Monday morning. Sentencing is scheduled for April 9.

Jennifer and James Crumbley are a rare case of parents being charged in connection with a shooting carried out by their son. James Crumbley, who also faces four counts of involuntary manslaughter, will have a separate trial in March.

The jury foreperson told an ABC News producer as she was walking to her car that the verdict "came down to the fact that Jennifer was the last adult with the gun."

Ethan Crumbley, who was 15 years old at the time of the shooting, has been sentenced to life in prison for killing four students and injuring seven others at Oxford High School. He had pleaded guilty to 24 charges, including first-degree premeditated murder and terrorism causing death.

In a dayslong trial, prosecutors presented damning evidence of the Crumbley parents -- who bought their son the gun used in the shooting -- failing to respond to warning signs exhibited by the shooter prior to the attack.

School officials had called the Crumbley parents to the school the morning of the shooting after finding violent drawings he had done on a school assignment. He was also caught searching online for bullets at school, watching shooting videos in class and drawing violent images on several other papers.

School officials testified that the parents chose not to take their son home despite the school telling them to get him immediate help, and offering them facilities that provided same-day mental health care services.

The parents told the school they could not take him home because they both had to return to work and that if he left school he would walk home and be alone. School officials, who were worried about his mental health, did not think it was a good idea for him to be alone since they were concerned he was considering suicide.

The parents chose to send him back to class and told the school that they would get him mental health care.

Jennifer Crumbley and her attorney Shannon Smith argued that the school had been "nonchalant" during the meeting and did not insist he be taken home.

During trial, the CEO of the company where Jennifer Crumbley worked testified that she could have left work if she needed to care for her son or she could have brought him back with her to the office. On the stand, Crumbley admitted that she would have been able to not return to work.

In text messages she sent after the shooting, Jennifer Crumbley told a man she was having an affair with -- long-time friend Brian Meloche -- that the shooting "could have been prevented" and that the school should not have allowed him to return to class.

Ethan Crumbley's parents purchased him the gun he used in the shooting as a gift and had taken him to the shooting range before the attack. Prosecutors argued that the parents did not secure the gun or limit their son's access to it.

Jennifer Crumbley testified that it was her husband's responsibility to ensure the gun was stored securely and that their son could not access it. One of the arguments made by her lawyer was that she did not know guns well.

Smith also argued that in Oxford, where the shooting happened, it is common for students to go hunting with guns. A school official testified that many seniors take prom portraits with their guns and that they often need to be reminded not to come to school with their guns during hunting season.

Families of shooting victims react

The parents of several of the students killed in the Oxford school shooting told "Good Morning America" Tuesday they were pleased with the verdict.

Steve St. Juliana, the father of Hana St. Juliana, said he was initially shocked and then relieved.

"The shock is I guess I didn't truly believe that they would come back with the guilty verdict -- and then obviously just relief that they had," he said. "They just looked at the evidence and used common sense and came back with the right verdict."

Craig Shilling, the father of Justin Shilling, said it came down to "accountability."

"There's this type of culpability out there now, that gross negligence is not acceptable in society," he said. "I hope it resonates in the minds of everybody for a long time. And I just hope that it creates some type of a change as it pertains to school shootings, these mass shootings and shootings in general."

Buck Myre, the father of Tate Myre, said he would like to see accountability for what he called the "whole systemic failure" that led to the shooting.

"It's easy to point the finger at the gun," he said. "That's the only thing that's being addressed, is the gun side of things, instead of the systemic side of things. It all needs to be addressed."

Extramarital affairs

In a turn of events, Jennifer Crumbley came under fire when a witness took the stand -- Meloche -- and it was revealed they were having an affair at the time of the shooting. In a previous ruling, Judge Cheryl Matthews had excluded all evidence pointing to Crumbley's extramarital affair from being used in the trial.

But, during the defense's questioning, Smith suggested that police intimidated and threatened Meloche into providing his testimony, so prosecutors pushed back and sought to allow the judge to include evidence that the two had an affair. Prosecutors argued that Meloche was not pressured, but that he didn't want information about their affair to become public.

The information regarding the affair was admitted into evidence and Crumbley later confirmed the affair when she took the stand in her own defense. She testified that they were having a six-month affair at the time of the shooting, meeting in a Costco parking lot during work hours.

Prosecutors argued that she spent a significant amount of time on her affair and taking care of her horses, often leaving her son alone and ignoring his messages. Crumbley said her affair only took place while her son was at school and that she always offered to take him with her when she went to see her horses, but he was not interested.

Prosecutors then pressed Jennifer Crumbley on her testimony, revealing that she had multiple affairs and together with Meloche had arranged meetups using Adult Friend Finder. Prosecutors revealed she had been using the app just two days before the shooting, but she did not meet up with anyone on that day.

Smith sought to defend Jennifer Crumbley as a mother who was doing the best that she could, at times giving examples from her own life as a mother and saying her house was just as messy as the photos the jury was shown of Crumbley's home.

- ABC News' Meredith Deliso and producer Janel Klein contributed to this report