OMAHA, Neb. -- An inmate that was previously convicted of charges in Douglas County was pronounced dead.

Officials said 45-year-old Bobby Wallace was found unresponsive in his cell at the Reception and Treatment Center (RTC) on Sunday.

Staff reportedly started CPR and contacted medical services. When they arrived, Wallace was pronounced dead.

According to court documents, Wallace was serving a 40- to 60-year sentence for charges out of Douglas County. He was convicted of second-degree murder, attempted second-degree assault, and use of a deadly weapon to commit a felony. Wallace started his sentence on Feb. 21, 2014.

As is the case whenever an inmate dies in the custody of the Nebraska Department of Correctional Services (NDCS), a grand jury will conduct an investigation.