LINCOLN–(KFOR May 19)–An inmate died at the Reception and Treatment Center in Lincoln.

The Nebraska Department of Corrections says 67-year-old Michael Gunther was serving a life sentence on charges of first degree murder and use of a firearm to commit a felony. Gunther committed the crimes in Sarpy County and began his sentence back in 2005. His cause of death isn’t known but the Department of Corrections said in a news release Gunther was being treated for a medical condition.

A grand jury will be conducting an investigation into the death.