An inmate at the Douglas County Detention Center died 12 hours after being booked into the jail, according to a news release from the Douglas County Sheriff’s Office.

According to the news release, the Douglas County Sheriff’s Office booked a 31-year-old man into a secluded cell around 5 a.m. on Thursday. While delivering the unidentified man his dinner, he was found unconscious around 5 p.m.

Deputies and medical personnel immediately started lifesaving efforts. Castle Rock Fire and Rescue responded to the scene to assist and took over lifesaving measures, eventually pronouncing the man dead around 6 p.m., the office said.

There were no signs of physical disturbances or suspicious activity. The sheriff’s office is now investigating the incident. Following investigations, the Douglas County Coroner’s Office will later identify the man.