Oxford High School used the active shooter drill known as ALICE (Alert, Lockdown, Inform, Counter, and Evacuate), which uses proactive strategies to evade a gunman, such as using noise as a distraction and creating distance.

[15] Earlier that month, following an act of vandalism—which included the hurling of a severed deer head from the school roof into the courtyard—school administrators published a note to parents, saying they had been investigating the rumors, but found no threat.

[3][20][21][22] According to students, a voice over the intercom alerted them to an active shooter, and their teachers started locking and barricading doors and covering windows, convincing them it was not a drill.

[31] At least one student posted a video to social media, showing people hiding in a classroom while someone out in the hallway spoke to them, claiming to be law enforcement.

[28][35][36] During a subsequent press conference, Sheriff Bouchard confirmed that, based on surveillance footage, Crumbley had never knocked on a door, and the person speaking from the hall was likely a detective trying to calm the students.

Officials told reporters that the cameras showed some of the actual shooting, and that Crumbley had a clear intent to kill other students, saying he fired through barricaded doors and aimed for the heads and chests of victims at close range.

[45][46][47] The cell phone contained two videos of Crumbley—both filmed the night before the incident—in which he purportedly talked about his plans to shoot and kill students at the school the following day.

[55] On December 6, prosecutor Karen McDonald said Oxford High School officials had legal grounds to search Crumbley's backpack and locker when concerns were raised about his behavior on the day of the shooting, but they never did so, for reasons which were not made clear.

[60] Crumbley was born in Atlantic Beach, Florida, 15 miles (20 km) east of Jacksonville, to parents Jennifer and James, both of whom had prior minor criminal records from 1995 to 2005 for DUI and check fraud.

A former neighbor told the Detroit Free Press that, shortly after the family's subsequent move to Michigan, in 2014 and 2015, Jennifer and James often left their son home alone and without a phone as they frequented bars in downtown Lake Orion.

As early as March 2021, he started sending his mother "disturbing texts about his state of mind," which included claims about "demons" and "ghosts" inside the home.

He also reportedly videotaped himself torturing animals, made Molotov cocktails, and sketched himself committing a school shooting, something he also joked about with a friend via text message.

[3][74][75] Prosecutors further alleged that at 1:22 p.m. – seven minutes after the first news reports came in of a shooting at the school and before any mention of who was responsible – Jennifer Crumbley texted her son, saying, "Ethan, don't do it."

[80] The terrorism charge is provided under Michigan law for "an act that is intended to intimidate or coerce a civilian population"— in this case, the Oxford High School community.

[85] At Crumbley's probable cause conference on December 13, Carniak postponed the upcoming preliminary examination to January 7, 2022, to allow prosecutors to review evidence.

As a juvenile, Crumbley was entitled to a hearing, under a 2012 U.S. Supreme Court ruling in Miller v. Alabama, to determine whether he would be eligible for parole after serving at least 25 years.

[95] On June 7, 2024, appellate attorneys for Ethan Crumbley filed a motion asking to withdraw the guilty plea and request a new sentencing, on the basis of ineffective assistance of counsel.

[79] On December 3, McDonald held a press conference in which she announced that both parents were being charged with four counts of involuntary manslaughter for their failure to secure the gun Crumbley used in the shooting.

[104] Shortly after, the Crumbleys' attorneys told the Detroit Free Press that their clients did not flee but rather left town for their own safety and would return to be arraigned.

[108] At around 11:05 p.m. on December 3, police received a tip from a business owner who found the Crumbleys' vehicle in his parking lot in Detroit, about 40 miles (64 km) from Oxford.

[56][120][121] During the Crumbleys' probable cause conference on December 14, a judge postponed their preliminary examination to February 8, 2022, while setting a bond hearing for January 7 of that year.

Crumbley's attorney also alleged inconsistent culpability theories by charging her son Ethan as an adult while also claiming that she had a responsibility to control her minor child, had no duty to protect the victims of the shooting, the jury instructions were flawed, and that she had ineffective assistance of counsel.

The complaint filed by the district's legal representatives claimed that a one-time dean of students had been included as a defendant; due to the survivors' attorney not removing him, the man had received death threats and suffered from significant emotional stress.

[131] The updated lawsuit included the principal and other administrators, accusing them of "gross negligence" and alleging that their actions "caused serious and permanent physical and emotional trauma."

[152] A memorial patch to commemorate the victims and the shooting was created for the Michigan Wolverines football team that was first worn on December 4, during the Big Ten Championship Game.

[159] Additional fundraisers for the victims and their families were seen on online crowdfunding pages, by local businesses, and by selling items such as T-shirts, to help cover medical, funeral, and other costs.

An additional statement was issued by TikTok, where a large majority of threats were allegedly identified as being made; the company removed many of the threatening videos posted and was working with law enforcement.

[167][168] In July 2024, it was reported that Thomas Matthew Crooks, the attempted assassin of Donald Trump, researched Ethan Crumbley and his family before his attack where he shot the U.S President in his right ear.

[169] President Joe Biden and U.S. Representative Elissa Slotkin, whose district includes Oxford High School, expressed their condolences over the shooting.

[170][171] Governor Gretchen Whitmer said in a statement that she was devastated for the students, staff, and families of the school, calling gun violence a "public health crisis".