TECUMSEH, Neb. (AP) — An inmate has died at the state prison in Tecumseh, and a grand jury will be convened to investigate.

The Nebraska Department of Correctional Services says in a news release that 47-year-old Todd Shade died at the prison on Sunday. The cause of Shade’s death has not been determined, but prison officials say he was being treated for a long-term medical condition.

Shade was serving a 100-year sentence on two counts of first-degree sexual assault of a child. He began serving his sentence in 1995.

State law requires a grand jury investigation anytime someone dies in state custody.