The suspect would then soon allegedly go on to shoot at least 11 people, with four killed at the time of this reporting.
What are the details?
Authorities said that the 15-year-old suspect — who is being tried as a adult and who faces terrorism charges in addition to murder and assault — may have had a gun in his backpack during a Monday meeting with administrators to discuss his deteriorating behavior.
At that point, however, no disciplinary action was warranted — at least according to the school superintendent.
"No discipline was warranted," Tim Throne, superintendent of the Oxford Community Schools district, said in a Thursday statement. "Yes, this student did have contact with our front office. And yes, his parents were on campus Nov. 30."
CNN reported Friday that Oakland County prosecutor Karen McDonald said that there's a "strong possibility" that the teen had a gun — which he reportedly used in the mass killing — during the morning meeting.
"During COVID, they don't use lockers, so they just have backpacks," she reasoned. "Unfortunately, he was allowed to get back to class, and we now know that he had a weapon with him at that time, and that is simply tragic."
The teen's parents could also face charges related to the shooting. Earlier this week, McDonald said that the gun the teen is believed to have used was purchased by his father on Black Friday.
"We know that owning a gun means securing it properly and locking it and keeping the ammunition separate and not allowing access to other individuals, particularly minors," McDonald said according to a report from the Detroit Free Press. "We have to hold individuals accountable who don't do that."
The teen suspect, if convicted on all charges, faces possible life in prison.
He has pleaded not guilty on all charges.