LINCOLN, Neb. (AP) — A Nebraska prisoner serving time for robbery and weapons convictions has died at a Lincoln hospital.

Officials say 22-year-old Daelan Lamere died Tuesday. Authorities have not confirmed the cause of his death, but prison officials say he tested positive for methamphetamine and ecstasy.

Prison officials say Lamere was found unresponsive in his cell at the Tecumseh State Correctional Institution on May 27. He was taken to a nearby hospital in Johnson County and later transferred to Bryan West in Lincoln, where he died.

Lamere was sentenced to 6 to 11 years in prison for four counts of robbery and one count of use of a deadly weapon to commit a felony in Douglas County. He was scheduled for release in September 2020.

The Nebraska State Patrol will investigate Lamere’s death.