Jail staff found the inmate unresponsive in his cell at about 6:40 p.m. Tuesday during a routine security check. Corrections officers and jail medical staff immediately tried to resuscitate the inmate.
Seattle Fire Department medics also were called in to continue life-saving measures, but the inmate was still unresponsive. He was pronounced dead at 7:18 p.m.
The inmate, later identified as Dion D. Duggins, 43, of Seattle, was booked into the King County Correctional Facility on Monday on an outstanding warrant.
The King County Medical Examiner's office will conduct a review to determine the cause and manner of death.