OKLAHOMA CITY (AP) — Law enforcement authorities say the death of a 57-year-old inmate at the Oklahoma County Jail appears to be the result of natural causes.

Officials say Richard Smith was found unresponsive in his cell on Monday. Oklahoma County Sheriff's Office investigators say Smith's death is apparently the result of a pre-existing medical condition.

Smith was booked into the Oklahoma County Jail on Sunday for driving under suspension and an outstanding Oklahoma County warrant for possession of a controlled dangerous substance. Authorities say that Smith was moved to the jail's medical wing based on information he provided to medical personnel.

The investigation is being conducted by sheriff's office officials as well as the Oklahoma State Bureau of Investigation.