Ethan Crumbly stands and addresses the court before being sentenced in Pontiac, Michigan, on Friday. AP

Ethan Crumbley was 15 years old at the time of the Nov.30, 2021 shooting at Oxford High School, north of Detroit, but was charged as an adult.

Oakland County Circuit Court Judge Kwame Rowe sentenced Crumbley, now 17, to life in prison without the possibility of parole.

Crumbley, who was wearing large black glasses and dressed in an orange prison jumpsuit, addressed the court before the sentencing, saying he was a "really bad person."

Parents of the victims and survivors of the mass shooting also spoke about the impact of the murders on their lives.

Kylie Ossege describes in detail how she had urged Hana St. Juliana a "thousand times" to keep breathing while they waited for help on a blood-soaked carpet, during her impact statement. AP

"For the past two years our family has been navigating our way through complete hell," said Buck Myre, whose son Tate was among those killed. "We miss Tate," Myre said. "Our family has a permanent hole in it that can never be fixed. Ever."

Crumbley pleaded guilty in October of last year to bringing a 9mm Sig Sauer handgun to school and opening fire on fellow students. Four classmates between the ages of 14 and 17 were killed and six other students and a teacher were wounded.

Parents facing charges

While school shootings carried out by teens have become a sadly familiar part of American life, it is highly unusual for parents to face charges.

Crumbley's parents, James and Jennifer Crumbley, have been charged with involuntary manslaughter.

They are accused not only of supplying their son with a weapon, but of ignoring escalating warnings that he appeared to be on the brink of violence.

James Crumbley allegedly bought the handgun for his son and his wife took the boy to a shooting range just days before the attack.

The Crumbleys were summoned to the school on the day of the shooting after a teacher was "alarmed" by a note she found on Ethan's desk. The parents were shown the drawing and advised they needed to get the boy into counseling. They allegedly resisted taking their son home and he returned to class.

He later entered a bathroom, emerged with the gun which had been concealed in his backpack and fired more than 30 shots.

The father of an Illinois man accused of killing seven people in July 2022 pleaded guilty in November to "reckless conduct" for helping his son obtain the assault rifle used in the mass shooting.