OKLAHOMA CITY – The Oklahoma County Detention Center’s Criminal Investigation Division is investigating the death of a detainee found unresponsive in his cell Monday evening.
It is the 7th detainee death of 2025 for the jail.
A detention officer conducting a welfare check around 5:37 p.m. discovered the detainee, later identified as Mario Mason, unresponsive, according to jail officials. Medical staff at the facility, along with EMSA and Oklahoma City Fire Department personnel, attempted life-saving measures before Mason was transported to a hospital.
He was pronounced dead at 6:46 p.m. by hospital medical staff.
Mason, 26, had been in custody since May 23, 2024. On April 24 of this year, he was sentenced to life in prison for first-degree murder and was awaiting transfer to the Oklahoma Department of Corrections.
The circumstances of his death remain under investigation.
Per protocol, all deaths in the Oklahoma County Jail are investigated as homicides by the Oklahoma County Detention Center until the Oklahoma Medical Examiner has determined the cause of death.
Officials said Mason’s family has been notified.
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