A 15-year-old boy charged with a school shooting in Michigan met with his parents and teachers about his behaviour hours before he murdered four classmates on Tuesday.
Ethan Crumbley is accused of opening fire at his high school in Oxford Township, in a rampage that saw eight others – including a teacher – injured.
The teenager, who appeared in court on Wednesday, is charged as an adult with one count of terrorism causing death, four counts of first-degree murder and seven counts of assault with intent to murder.
Prosecutor Karen McDonald did not reveal any motive for the shooting in the community of about 22,000 people roughly 30 miles north of Detroit.
She said prosecutors were “confident” they could demonstrate the crime was premeditated, adding: “There is a mountain of digital evidence. Videotape, social media, all digital evidence possible.”
Sheriff’s Lieutenant Tim Willis told a judge that Crumbley recorded a video the night before the violence in which he discussed killing students.
Earlier, Oakland County Sheriff Mike Bouchard told reporters that Crumbley’s parents were called to the school on Tuesday “for behaviour in the classroom that was concerning”.
The teen remained in school, and the shooting occurred a few hours later.
The court heard how Crumbley entered a bathroom with a backpack and came out with a semi-automatic handgun, firing at students while moving down the hallway.
Deputies rushed to the school around lunchtime and captured Crumbley within minutes of the shooting.
His father bought the 9mm Sig Sauer gun used in the attack last week, according to Mr Bouchard. When Crumbley was arrested he had an additional 18 rounds of ammunition on him.
It came after the Sheriff’s Office identified the latest victim as teenager Justin Shilling.
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The 17-year-old died at around 10am on Wednesday at McLaren Oakland Hospital in Pontiac, Michigan. The other victims were 16-year-old Tate Myre, 14-year-old Hana St Juliana and 17-year-old Madisyn Baldwin.
Mr Myre died in a patrol car as a deputy tried to get him to an emergency room.
Investigators are still trying to determine a motive for the shooting at Oxford High School.
Authorities were made aware of posts Crumbley shared on social media that said there had been threats of a shooting at the roughly 1,700-student school, but Mr Bouchard said they didn’t know about the rumours until after the attack.
“The person that’s got the most insight and the motive is not talking,” he added at a news conference.
He said that Crumbley had no previous run-ins with his department and he was not aware of any disciplinary history.
The campus was placed on lockdown during the attack, with some children sheltering in locked classrooms.
Footage captured by a student also showed people huddled under desks. They were later taken to a nearby grocery store to be picked up by their parents.
Isabel Flores, a 15-year-old, told WJBK-TV that she and other students heard gunshots and saw another student bleeding from the face. They then ran from the area through the rear of the school, she said.
A teacher who received a graze wound to the shoulder was taken to hospital but has now left.
Seven more students ranging from 14 to 17 remained in hospital through the night with gunshot wounds, Mr Bouchard said.