On two audio recordings, played before a court hearing on 27 July, Crumbley boasts of trying to kill as many students as he can, and the enjoyment he will take from it.
“My name is Ethan Crumbley, age 15, and I am going to be the next school shooter,” he says on one recording.
“I’ve thought about this a lot. I can’t stop thinking about it. But it’s constantly in my head.”
In a second audio, he says: “I’m gonna have so much fun tomorrow.”
Crumbley, 17, pleaded guilty to one count of terrorism causing death, four counts of first-degree murder and 19 other charges stemming from the mass shooting he committed on 30 November 2021 at the age of 15.
Although even given the heinous, premeditated nature of his crimes were not a foregone conclusion, Crumbley was eventually sentenced to life without the possibility of parole on 8 December.
His attorneys launched an appeal of his sentence in January.
Crumbley’s parents Jennifer and James Crumbley have pleaded not guilty to four counts of involuntary manslaughter in connection with the shooting. The parents are being tried separately.
James Crumbley’s trial is set to begin on 5 March while Jennifer Crumbley’s trial is underway.
‘I want America to hear what I did’
In court, Crumbley’s excerpts from the teenager’s 22-page handwritten journal read out by lead investigator Lt Timothy Willis provided a horrifying insight into his state of mind in the lead-up to the shooting.
“I want to shoot up the school so f***ing badly,” Crumbley writes in one entry of the journal, recovered from his backpack in a school bathroom after the shooting.
“The first victim has to be a pretty girl with a future so she can suffer just like me.”
“I want America to hear what I did,” he also wrote. “I will cause the largest school shooting in the state. I wish to hear the screams of the children as I shoot them.”
Crumbley laid out how the shooting would transpire. “I will continue shooting people until police breach the building,” he wrote. “I will then surrender to them and plead guilty to life in prison.”
In the week leading up to the killings, Crumbley searched online about the death penalty in Michigan and prison sentences for 15-year-olds.
In audio recordings, he outlined how his life had declined and the anger he felt towards the world and his need to teach other students a “lesson”.
“I will walk behind someone, and I will shoot a bullet into their skull. And that’s the first victim,” he said. “I’m gonna open fire on everyone in the hallway… I will try to hit as many people as I can. I will reload, and I will find people hiding. I want to teach them a lesson of how they are wrong, of how they are being brainwashed.”
Crumbley looked down at the desk as the audio was played, according to CNN.
Defence lawyer Paulette Michel Loftin read out a separate passage of the journal to show evidence of Crumbley’s deteriorating mental health.
“I can feel the evil around me and even dogs sense it. ... I don’t want to be evil,” Crumbley wrote.
“I want help but my parents don’t listen to me so I can’t get any help. I feel like I’m in a tiny loop of sadness.”
Ms Loftin argued that Crumbley was not “irreparably corrupt”.
The court were also shown text messages between Crumbley and an unnamed friend in which he describes how he tortured and killed baby birds.
Disturbing red flags
The weekend before the shooting, prosecutors say James Crumbley purchased the Sig Sauer 9mm used in the attack at a gun store in Oxford.
His mother Jennifer Crumbley posted a message on social media that weekend saying, “mom and son day testing out his new Christmas present,” according to prosecutors.
Previous court hearings have heard alarming details about potential red flags that were missed by school officials.
On 29 November, a teacher caught Crumbley searching for ammunition online, prosecutors say. School officials contacted Crumbley’s parents by phone and email, but they did not answer.
Jennifer Crumbley allegedly texted her son that day, saying: “LOL I’m not mad at you. You have to learn not to get caught.”
On the day of the shooting, a teacher found a drawing on Crumbley’s desk depicting a school massacre.
The illustration showed a semiautomatic handgun pointing at the words “the thoughts won’t stop help me,” prosecutors said. It also depicted a drawing of a bullet with the words “blood everywhere” written above it.
The words “my life is useless” and “the world is dead” were also seen next to a laughing emoji.
Crumbley and his parents were called to a disciplinary meeting that day, where school officials instructed them to seek counseling. Crumbley had the gun in his backpack at the meeting, according to prosecutors.
Counsellors were satisfied with his claims that the scrawls were merely designs for a video game and neither his bag nor locker were searched
Crumbley’s parents argued they didn’t want him to be taken out of school, and he returned to the classroom.
How the shooting unfolded
School surveillance footage showed Crumbley enter a bathroom with a backpack at 12.51pm, before emerging about a minute later.
He then walked “methodically and deliberately” through the school hallway firing into classrooms and at fleeing students, prosecutors say. Shell casings recovered from the school showed he had fired at least 30 shots.
Police received more than 100 911 calls from terrified students, and officers rushed to the scene.
Students would later tell CNN how they armed themselves with scissors to fight back.
Crumbley was apprehended within two to three minutes of officers arriving, Oakland County Sheriff Michael Bouchard said at the time.
Madisyn Baldwin, 17 and Hana St. Juliana, 14, were pronounced dead at the scene.
Tate Myre, 16, a popular member of the school’s football team, is said to have attempted to disarm the shooter, and succumbed to his wounds in a patrol car as a deputy tried to rush him to hospital.
Justin Shilling, 17, died the next day in hospital.
Arraignment, terror charges, and lawsuits
At a court appearance in early December 2021, Crumbley was charged as an adult with 24 crimes including terrorism and murder.
On 3 December, his parents were charged with involuntary manslaughter. They were arrested in Detroit the next day by US Marshalls after failing to appear in court.
They have been ordered to stand trial after a Michigan court of appeals ruled there was enough evidence against them in March.
Two weeks after the shooting, attorneys for two sisters who survived the mass shooting accused the school district in a $100m lawsuit of deleting social media accounts and scrubbing the school website of administrators while the investigation is under way.
“Not only did defendants fail to take necessary steps to preserve the evidence, but they willfully destructed the evidence by deleting the webpages and social media accounts,” attorney Nora Hanna wrote in the court filing, seen by the Detroit Free Press.
“Plaintiffs cannot continue to be blindsided by the defendants by having to search for what evidence is being destroyed or altered.”
An attorney for the school district branded the claims a “disgusting” lie.
In January 2022, survivors filed an amended lawsuit against the school principal and other administrators alleging "gross negligence" that had caused "caused serious and permanent physical and emotional trauma”.
Crumbley pleaded guilty to all charges in October 2022.
In June, prosecutors said the teenager had been “exhibiting sporadic, disturbing behaviour” in jail.
On 13 February 2023, a gunman armed with an AR-15-style weapon killed three students and wounded at least five others in a shooting at Michigan State University.
Among the students sheltering in place were several traumatised survivors of the Oxford High School shooting.
Jennifer Mancini, told the Detroit Free Press that the shooting had retraumatised her daughter after losing two close friends in the Oxford school shooting.
“She said she can’t believe this is happening again,” Ms Mancini told the Free Press.
At least two other MSU students had survived both shootings.
Crumbley speaks at sentencing hearing as judge hands down life in prison
Family members of the four students killed at Oxford High School on 30 November 2021 gave heart-wrenching victim impact statements during an emotional hearing at an Oakland County courtroom on 8 December.
Judge Kwamé Rowe then handed down a life sentence without the possibility of parole.
Because Crumbley was 15 at the time of the shooting, there was also a possibility that he could have received a shorter sentence — anywhere from 25 years to 40 years — that would have eventually made him eligible for release by the state parole board.
Crumbley addressed the court and apologised to the victims’s families, also asking the judge to grant the sentence that survivors saw fit. Crumbley said he “was trying to change” and was already making progress, seemingly showing remorse for the four lives that he cut short and the countless others that he impacted.
“All I want is for the people I’ve hurt to have a final sense that justice somewhat was served in any fit capacity that they recognise,” Crumbley said. “Any sentence that they ask for, I ask that you impose it on me. Because I want them to be happy, I want them to feel secure and safe. I do not want them to worry another day.
“But I really am sorry for what I’ve done and what I’ve taken from them, I cannot give it back, but I can try my best in the future to help other people and that’s what I’ll do.”
His attorneys had previously tried to argue that Crumbley could benefit from rehabilitation and a chance at freedom decades from now. But Judge Rowe said that the evidence suggested Crumbley carried out the attack with the sole purpose of causing harm and because he wanted to go down in history as “the biggest shooter.”
“The court cannot ignore that,” Judge Rowe told the court. “He has an obsession with violence. This act involved extensive planning and research and he executed every last thing that he planned.”
The judge also addressed victims in the courtroom.
“I know that whatever sentence the court imposes will not bring your loved one back or cure the mental anguish or lifelong physical scars that some of you have,” he said. “But I hope that this sentence does allow you to close a chapter in your life.”
Crumbley remained emotionless and stared down at the table as families of the victims and survivors of the attack shared with the court the horrors they experienced on the day of the shooting.