Authorities say the 53-year-old was found hanging in his cell from a bed sheet around 9:20 p.m. Tuesday at the Correctional Reception Center in Orient. Facility staff tried to resuscitate him, and he was taken to a hospital, where he was pronounced dead.
"These degenerate molesters are cowards. They con and capture vulnerable children. This man couldn't take, for even a month, a small portion of what he had dished out for more than a decade," said Cuyahoga County Prosecutor Timothy J. McGinty in a statement. "Let this be a message to other child kidnappers: There will be a heavy price to pay when you are caught. You won't enjoy the captive side of the bars."
According to ABC News, Castro had been in protective custody, meaning he was in a cell by himself and was checked by correctional facility staff every 30 minutes. He was taken off suicide watch in June, which entails constant supervision, after authorities concluded he was not a suicide risk.
Castro pleaded guilty to 937 counts of rape, kidnapping and aggravated murder. He was sentenced Aug. 1 to life in prison plus 1,000 years without the possibility of parole.
He had been living alone in a 12- by 8-foot cell and only had an hour a day outside the cell. Officials said his solitary confinement was intended to protect him, not punish him.
Gina DeJesus, Michelle Knight and Amanda Berry were held captive and raped in Castro's house for years. All three victims are aware of Castro's death and will not be making a statement. However, DeJesus' brother told ABC News they are all doing OK.
The three women disappeared separately between 2002 and 2004 after accepting rides from Castro. They escaped his home May 6, when Berry, now 27, broke part of a door and yelled to neighbors for help. Castro was arrested that night.
The American Civil Liberties Union of Ohio asked the prison system to conduct a full investigation of the death.
The Associated Press contributed to this report.