LINCOLN, Neb. -- A 92-year-old inmate has died at the Nebraska State Penitentiary. 

Nebraska's Department of Correctional Services says Lawrence Ortiz died Monday night. 

Ortiz was sentenced to life in prison for first-degree murder in Buffalo County. He began his sentence in 1971. 

Authorities say the cause of death has not yet been determined but did say Ortiz was being treated for long-term medical conditions. 

An investigation will be conducted.