Ariel Castro, 53, was found hanging around 9:20 p.m. Tuesday at the state prison in Orient, said JoEllen Smith, a spokeswoman for the corrections system. Prison medical staff performed CPR before Castro was taken to a hospital, where he was pronounced dead.
Castro had been in protective custody because of the notoriety of his case, meaning he was checked every 30 minutes, but was not on suicide watch, which entails constant supervision, Smith said.
An autopsy showed the death was suicide by hanging, said Dr. Jan Gorniak, Franklin County coroner. Gorniak would not comment on the circumstances in which Castro was found.
In Castro's old Cleveland neighborhood, Jessica Burchett, 19, said his death had short-circuited the life sentence called for in his plea bargain.
"It does give a little bit of closure to the families and people that got affected by what he did, but at the same time he deserved to be in there for his life because of what he did to those girls," she said.
Elsie Cintron, a neighbor who lived up the street from Castro, said the suicide left her with mixed feelings.
"He took the coward's way out," Cintron said. "We're sad to hear that he's dead, but at the same time, we're happy he's gone, and now we know he can't ask for an appeal or try for one if he's acting like he's crazy."
No one answered the door Wednesday morning at the home of Castro's mother and brother.
The three women - Amanda Berry, Gina DeJesus and Michelle Knight - disappeared separately between 2002 and 2004, when they were 14, 16 and 20 years old. They were rescued from Castro's home on May 6 when Berry broke out part of screen door and yelled to neighbors for help.
Elation over the women's rescue soon turned to shock as details emerged about their captivity. Castro fathered a child with Berry while she was being held. The girl was 6 when she was freed.
Investigators also said the women were bound with chains, repeatedly raped and deprived of food and bathroom facilities. Knight told investigators she was beaten and starved to force her to miscarry over and over.
Castro was sentenced Aug. 1 to life in prison plus 1,000 years after he pleaded to 937 counts, including kidnapping and rape, in a deal to avoid the death penalty. At his sentencing, he told the judge: "I'm not a monster. I'm sick."
At the home of Berry's sister, a woman who didn't identify herself said from the porch Wednesday there would be no comment. An officer in a passing patrol car kept watch on the street.
Wearing their familiar red berets, members of the Guardian Angels volunteer patrol group stationed themselves outside DeJesus' and said her family didn't want to be bothered as the community absorbed the news.
Cleveland Mayor Frank Jackson said in a statement: "I ask the community to continue to respect the privacy of the survivors so that they can move forward with their lives."
Messages left for the women's lawyers were not immediately returned.
Castro was watched closely in the Cuyahoga County Jail in the several weeks after his arrest and before his guilty plea, with logs noting his activity every 10 minutes. He was taken off the suicide watch in June after authorities determined he was not a suicide risk.
Castro's attorneys tried unsuccessfully to have a psychological examination of Castro done at the jail before he was turned over to state authorities following his guilty plea, his attorney, Jaye Schlachet, said Wednesday. Schlachet would not comment further.
In an interview last month, Schlachet and attorney Craig Weintraub said that their client clearly fit the profile of sociopathic disorder and that they hoped researchers would study him for clues that could be used to stop other predators.
Associated Press writers Thomas J. Sheeran in Cleveland and Kantele Franko in Columbus contributed to this report.