MILWAUKEE (CBS 58) -- Tuesday night around 10:00 p.m. a 51-year-old inmate at the Milwaukee County Jail complained of not feeling well. Medical staff immediately responded to assess his condition and called for an ambulance.

The inmate lost consciousness at the jail clinic, and immediate CPR lifesaving efforts by jail staff and firefighters were unsuccessful to revive him. He was pronounced dead by MFD paramedics.

The inmate was brought in to the jail on Tuesday morning at 2:30 a.m. by MPD. An autopsy by the Medical Examiner revealed advanced heart disease and a blood clot.

Waukesha County Sheriff’s Department detectives are handling the death investigation.