TAHLEQUAH, Oklahoma - The Oklahoma State Bureau of Investigation is looking into the death of a 53-year-old man in the Tahlequah city jail on Monday. Police Chief Nate King told the Tahlequah Daily Press he believes Jerry Batt died of natural causes.

King says Batt went to bed around midnight and was later discovered dead. Batt had assisted with a cleanup at the jail before his death. The state Medical Examiner's Office is performing an autopsy.

King says his department asked the OSBI to investigate the death.

The Associated Press contributed to this report.