The mother and father of a Michigan teenager who shot and killed four classmates were each sentenced to between 10 and 15 years in prison on Tuesday after a jury convicted them of manslaughter in a rare case of parents being held responsible in a school shooting.

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' defence 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. (Reuters)