A teenager who killed four fellow students at a Michigan high school in 2021 wrote about his plans in a handwritten journal, detailing how he would target his victims and make himself famous, according to evidence offered Thursday.

The lead investigator was the first witness at a unique hearing to determine whether Ethan Crumbley will be sentenced to life in prison or receive a shorter term with an opportunity for parole.

Lt. Timothy Willis said a 22-page journal was found in a bathroom stall, apparently left behind by Crumbley before he emerged in a hallway at Oxford High School and began shooting.

“I want America to hear what I did,” Crumbley wrote. “I will cause the largest school shooting in the state. I wish to hear the screams of the children as I shoot them.”

Willis said Crumbley searched the internet for information about police emergency response times, prison sentences for teenagers and whether Michigan has the death penalty.

There is no dispute that Crumbley killed four fellow students and wounded seven other people. But because he was 15 at the time, he can’t automatically be given a life sentence.

A no-parole sentence is rare for Michigan teens convicted of first-degree murder since the U.S. Supreme Court in 2012 said minors must be viewed differently than adults.

Life in prison “will only be imposed on a juvenile who’s believed to be incorrigible, unredeemable and with no reasonable expectation of rehabilitation,” said Margaret Raben, former president of a statewide association of defense attorneys.

Judge Kwame Rowe has set aside at least two days for the hearing but isn’t expected to make an immediate decision. Crumbley’s lawyers will argue that he should be released at some point, claiming that the violence was the catastrophic climax of the teen’s untreated mental illness and “abhorrent family life.”

In her opening remarks, Oakland County prosecutor Karen McDonald said Crumbley was an “offender like no other,” meticulously planning the attack and willing to peacefully surrender to spend his life behind bars.

“We must tell the truth. Our witnesses must tell the truth, and we will tell all of it,” McDonald told the judge in support of a life sentence.

Crumbley, now 17, also could be given a minimum sentence somewhere from 25 years to 40 years. He would then be eligible for parole, though the parole board has much discretion to keep a prisoner in custody.

On the day of the shooting, Crumbley and his parents had met with school staff after a teacher was troubled by drawings that included a bloody body and a gun pointing at the words, “The thoughts won’t stop. Help me.”

Crumbley was allowed to stay in school, about 40 miles (64 kilometers) north of Detroit, though his backpack was not checked for weapons. He later emerged from a bathroom with a pistol.

He pleaded guilty to 24 charges, including first-degree murder, attempted murder and terrorism. Prosecutors insist Crumbley’s decisions can’t be mitigated by his young age or immaturity.

Crumbley “took extensive time to research, plan and prepare for the school shooting, and he expressly considered the results, risks and consequences of his actions — specifically contemplating that he would spend the rest of his life in prison,” assistant prosecutor Marc Keast said in a court filing.

Crumbley’s lawyers plan to offer testimony from an expert in child brain development and another who has spent time with the teen and performed psychological tests.

Crumbley is “not one of those rare individuals who is irreparably corrupt and can’t be rehabilitated,” attorney Paulette Michel Loftin said in her opening statement.

Roughly 300 people who were serving mandatory life sentences have returned to Michigan’s local courts and received shorter sentences as a result of the Supreme Court’s groundbreaking decisions about how to assess U.S. teens convicted of murder, according to the State Appellate Defender Office.

Crumbley’s parents, James and Jennifer Crumbley, are separately charged with involuntary manslaughter in the shooting. They’re accused of buying a gun for their son and ignoring his mental health needs.

(AP)