Ariel Castro, the fiend who held 3 women hostage in his Cleveland house of horrors, has committed suicide behind bars.

Castro, 53, was found hanging in his cell around 9:20 p.m. at the Correctional Reception Center in Orient, a Department of Rehabilitation and Correction spokeswoman, told media.

Prison medical staff performed CPR on Castro before he was rushed to a hospital where he arrived dead on arrival at 10:50 p.m.

Castro had been in protective custody of the notoriety of his case, but was not on suicide watch.

As The ENQUIRER previously reported Castro was sentenced Aug. 1 to life in prison plus 1,000 years after pleading guilty on 937 counts — including kidnapping and rape.