Corrections officials in Ohio say Ariel Castro is believed to have committed suicide in his cell Tuesday night.
They say he was found hanged around 9:20 p.m. ET at the Correctional Reception Center in Orient.
Castro was serving a life sentence for holding three women captive in his Cleveland home for more than a decade.
Officials say medical staff at the prison tried to revive Castro. He was pronounced dead at a hospital around 10:50 p.m. ET.
Castro was moved to the prison in Orient for his safety. He first was sent to the Lorain Correctional Institution for processing.
In July, Castro pleaded guilty to hundreds of charges including kidnapping and rape. He was sentenced in August to life in prison plus 1,000 years.