TECUMSEH, Neb. (AP) — A grand jury will look into the prison death of a Nebraska inmate who attacked a state caseworker in 2011.

A Nebraska Department of Correctional Services news release says a prison worker found 42-year-old Patrick Howley unresponsive in his cell at Tecumseh state prison just before 7 a.m. on July 27. Howley was pronounced dead less than an hour later at Johnson County Hospital in Tecumseh. Officials suspect that Howley killed himself.

Johnson County Attorney Julie Smith on Tuesday told The Associated Press that autopsy results have not yet returned. Under Nebraska law, a grand jury investigates whenever someone dies in custody or while being taken into custody.

Howley was serving a sentence of 116 to 162 years for trying to kill a Lincoln Correctional Center caseworker.