Jennifer and James Crumbley, Ethan Crumbley's parents, were sentenced immediately after several parents of the victims gave emotional statements in an Oakland County courtroom in Pontiac, Michigan.
"Not only did your son kill my daughter, but you both did as well," Nicole Beausoleil, 17-year-old Madisyn Baldwin's mother, told the court as she wept. James Crumbley sat impassively while his wife, Jennifer, hung her head.
Their son was 15 at the time of the shooting at Oxford High School in 2021, in which four students were killed and six other students and a teacher were wounded. Ethan pleaded guilty the following year to four counts of first-degree murder and other charges, and was sentenced to life in prison without parole in December.
In remarks to the court before sentencing, Jennifer Crumbley, 46, expressed her "deepest sorrow" and said she had had no inkling her son was capable of killing.
"My husband and I used to say we have the perfect kid. I truly believed that," she said. "I didn't have a reason to do anything different. This is not something I foresaw."
"I will be in my own internal prison for the rest of my life," she said, naming her son's victims several times. "If there's anything the general public can take away from this, it's that this could happen to you, too."
Addressing the court, her 47-year-old husband said, "I am sorry for your loss as a result of what my son did. My heart pours out to every single one of you."
In handing down the sentences, Circuit Court Judge Cheryl Matthews said the convictions were not about poor parenting. She said James Crumbley was responsible for his son's "unfettered access" to the murder weapon and that Jennifer Crumbley glorified guns.
"These convictions confirm repeated acts or lack of acts that could have halted an oncoming runaway train, about repeatedly ignoring things that make a reasonable person feel the hair on the back of their neck stand up," the judge said.
Prosecutors in the trials of both Crumbleys said the parents were criminally negligent for giving their child a 9mm semi-automatic pistol as a Christmas present and for ignoring signs his mental health had deteriorated and that he was potentially violent.
The parents' defense teams argued, among other points, that it was impossible for the mother and the father to envision their son would carry out a mass shooting.
The U.S., a country with persistent gun violence, has experienced a series of school shootings over decades, often carried out by current or former students.
There is little precedent for the criminal charges faced by the Crumbleys, who are the first parents known to be charged with manslaughter in a school shooting carried out by one of their children.
Experts and gun safety advocates have said their trials were an important step in holding gun-owning parents more accountable for school violence carried out by their children. Studies by the U.S. Department of Homeland Security have shown that around 75% of all school shooters obtained their weapons at home.
James Crumbley purchased the handgun as a Christmas present for Ethan just four days before the Nov. 30, 2021, shooting.
On the morning of the rampage, both parents were summoned to their son's school after teachers discovered violent messages and drawings on his schoolwork, prosecutors said during the trials.
The Crumbleys were told Ethan needed immediate counseling. But prosecutors said the couple resisted taking the teen home that day, and didn't search his backpack or ask him about the gun they knew he could access.
Ethan Crumbley was returned to class. He later walked out of a bathroom with the gun and began firing, according to prosecutors.
