The Oklahoma County Detention Center said a 65-year-old female inmate died in custody just before 10 p.m. Tuesday.
According to authorities, the inmate was on suicide watch, but officials do not believe suicide or foul play were involved.
The state medical examiner is investigating the cause of death.
This is the 10th inmate death at the detention center since last July.
The inmate was identified as Christa Sullivan.
This is a developing story.