DETROIT -- The disclosure about Ethan Crumbley, 17, was made in a court document this week and at a routine monthly hearing Friday in Oakland County court.
Prosecutors did not offer any details in public but shared them privately with Judge Kwame Rowe and Crumbley's attorneys.
Crumbley pleaded guilty to murder, terrorism and other charges for a mass shooting at Oxford High School in 2021. Four fellow students were killed and seven more people were wounded.
Crumbley is being held at the county jail but is kept away from adults who are also in custody.
He has "started exhibiting sporadic, disturbing behavior," assistant prosecutor Marc Keast said in a court filing. "This behavior has been documented via report and body-worn camera from jail personnel responding to various incidents. It is not readily apparent what the impetus for or cause is of this behavior."
Crumbley was 15 at the time of the shooting. First-degree murder carries a mandatory life sentence in Michigan. But because of his age, Crumbley is entitled to a hearing where Rowe will hear testimony about his family life, mental health and other factors and decide whether a shorter sentence would be appropriate.
Keast and Crumbley's attorneys said they still believe he is mentally competent for the sentencing phase of the case. The hearing starts July 27.
Separately, his parents, James and Jennifer Crumbley, face involuntary manslaughter charges. They're accused of ignoring their son's mental health needs and making a gun accessible at home.
