The Madison County Sheriff’s Office is investigating the death of an inmate while at the county jail.

John Mitchell Rigdon, 68, was found unresponsive in his medical cell at about 4:30 a.m. Monday. Sheriff’s detention officers and medical staff began life-saving measures. but Rigdon was pronounced dead, the sheriff’s office said in a news release.

“An in-custody death is always difficult for everyone involved: facility staff members, medical staff, and emergency first responders,” Sheriff Kevin Turner said. “We are extremely saddened to report the death of Mr. Rigdon and send our heartfelt condolences to his family and loved ones during this difficult time.”

The cause of death is was not immediately known and will be established through autopsy and toxicology reports conducted by the Alabama Department of Forensic Sciences.

Huntsville Police officers arrested Rigdon, 68, charging him with criminal trespassing in the third degree, after an incident Sunday at Crestwood Hospital.

Rigdon had been discharged from the hospital earlier in the day. but returned, and Crestwood Hospital personnel contacted the Huntsville Police Department, requesting their assistance. Upon arrival, officers arrested Rigdon and took him to the Madison County Sheriff’s facility for processing and detention.

At the Madison County Jail, sheriff’s office medical personnel found Rigdon had a history of medical issues and was suffering from a terminal condition, and he was placed in the jail infirmary. An on-call doctor was notified and wrote medical orders for Rigdon, the sheriff’s office said.