Both parents James and Jennifer Crumbley will be sentenced on April 9, with manslaughter carrying a penalty of up to 15 years in prison.
James Crumbley, 47, was found guilty on Thursday, a month after his wife, Jennifer Crumbley, 45, was found guilty on manslaughter charges in February related to the shooting. James Crumbley faced four counts of involuntary manslaughter, one for each of the victims in the 2021 shooting.
The couple faced separate trials and were the first parents in the US to be charged in a mass school shooting committed by their child. Ethan Crumbley was 15 at the time of the attack on Oxford High School and used a semi-automatic handgun.
The verdicts were read around 7:15pm (02:15 GMT) at the end of a full day of deliberations in Oakland County court.
Both will be sentenced on April 9. Manslaughter carries a penalty of up to 15 years in prison.
Ethan pleaded guilty in 2022 to four counts of first-degree murder and other charges and was sentenced to life in prison without parole in December. The US, a country with persistent gun violence, has experienced a series of school shootings over the years, often carried out by current or former students.
“This is a very egregious and rare, rare set of facts,” Karen McDonald, the prosecutor for Oakland County, Michigan, told the jury during closing arguments on Wednesday.
McDonald said James Crumbley repeatedly ignored warning signs that his son was deeply disturbed, did not get him the help he needed, and did not do enough to safely store the firearm in the family home.
“He did nothing over and over and over again,” McDonald said.
McDonald also presented the jury with texts that the teenager had sent to a friend and journal entries he had written in the months leading up to the shooting, in which he talked about wanting medical attention and hearing voices but expressing concern his parent would be “p*****”.
On one occasion, according to a text message to a friend, McDonald said Ethan had asked James Crumbley to take him to the doctor, but his dad “gave me some pills and told me to suck it up”.
Mariell Lehman, a defence lawyer, argued that James Crumbley could not have possibly foreseen that his son would carry out a mass shooting.
“James had no idea that his son was having a hard time,” Lehman told jurors during her closing argument, saying no evidence had been presented that James knew the contents of his son’s text messages or journal.
‘Blood everywhere’
Gun safety experts have said they hope the Crumbley trials serve as a wake-up call for parents to better secure weapons in their homes. About 75 percent of school shooters got the guns used in attacks from their own homes, according to government research.
According to prosecutors, James Crumbley bought the handgun used in the attack four days before the shooting on November 30, 2021.
That morning, a teacher discovered drawings by Ethan Crumbley that depicted a handgun, a bullet and a bleeding figure next to the words “Blood everywhere”, “My life is useless”, and “The thoughts won’t stop – help me”.
The Crumbleys, summoned to the school that morning, were told that Ethan needed counselling and they needed to take him home, according to prosecutors. But the couple resisted taking their son home and did not search his backpack or ask him about the gun, prosecutors said.
Both of the Crumbleys challenged that account in their trials, claiming that teachers in the meeting mutually agreed that Ethan could remain in school that day, and that at no point did they think he posed a danger to the other students.
Ethan was returned to class and later walked out of a toilet with the gun and began firing, according to prosecutors.
Ethan killed Justin Shilling, 17; Madisyn Baldwin, 17; Hana St Juliana, 14; and Tate Myre, 16. Six more students and a faculty member were wounded. No one had checked the backpack, although a school administrator had joked it was heavy.
