A Payson inmate serving a sentence in the Globe jail was found dead in his cell shortly after breakfast Tuesday morning.
Sheriff's deputies have not released the man's name, since his family had not yet been notified.
According to Capt. Bill Blank, the 52-year-old man had been experiencing some health problems since his incarceration, and had been seen by doctors twice while he was in jail.
"He was monitored through the night, and he was checked approximately 10 minutes apart," Blank said. "He was delivered breakfast this morning, and was still breathing at that time. When guards checked on him 10 minutes later, he was not breathing."
Paramedics responded to the jail and attempted lifesaving measures, but were unsuccessful.
Blank said the inmate was the single occupant of his cell, and believes death was due to natural causes.
"There was no apparent trauma or suicide," he said.
The inmate was transported to the Pima County Medical Examiner for autopsy to determine the exact cause of death.