Ohio prisons director Gary Mohr ordered two reviews Wednesday, less than a day after Castro was found in his cell and medical responders were unable to revive him.
One review will look at the suicide — normal in such cases — while the other is an examination of Castro's circumstances, and whether he received the proper medical and mental health care leading up to his suicide.
The American Civil Liberties Union of Ohio called for an investigation into Castro's death as well as the question of whether all inmates are getting the mental health treatment they need.
"As horrifying as Mr. Castro's crimes may be, the state has a responsibility to ensure his safety from himself and others," ACLU of Ohio Executive Director Christine Link said in a statement.
Castro, 53, had been taken off suicide watch while in county jail and was in protective custody in prison, a status reserved for high-profile inmates who could be in danger from other inmates.
As part of that status, he was in a cell by himself being checked every 30 minutes at an inmate intake prison south of Columbus, said JoEllen Smith, a Rehabilitation and Correction Department spokeswoman.
Prison medical staff performed CPR before Castro was taken to a hospital, where he was pronounced dead. State police are also investigating.
Residents in the westside Cleveland neighborhood where three women were secretly imprisoned reacted with scorn and grim satisfaction Wednesday to Castro's death.
"He took the coward's way out," said Elsie Cintron, who lived up the street from the former school bus driver. "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."
Even the prosecutor joined in.
"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 Tim McGinty.
Castro was sentenced Aug. 1 to life in prison plus 1,000 years after pleading guilty to 937 counts, including kidnapping and rape, in a deal to avoid the death penalty. "I'm not a monster. I'm sick," he told the judge at sentencing.
Castro's captives — Amanda Berry, Gina DeJesus and Michelle Knight — disappeared separately between 2002 and 2004, when they were 14, 16 and 20. They were rescued from Castro's run-down house May 6 when Berry broke through a screen door.
Elation over the women's rescue 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 disclosed that the women were bound with chains, repeatedly raped and deprived of food and bathroom facilities.
Castro's lawyers tried unsuccessfully to have a psychological examination of Castro done in jail before he was turned over to state authorities, his attorney, Jaye Schlachet, said Wednesday.
Michael Casey, director of the Suburban Law Enforcement Academy outside Chicago, said a notorious figure like Castro would have been more apt to be harmed by other inmates, citing the case of Jeffrey Dahmer, the Milwaukee cannibal who was slain behind bars in 1994.
He said that given the way Castro managed to hide his crimes for so long, he probably would have been able to conceal any suicidal tendencies from his jailers.
The prison where Castro hanged himself, a so-called reception center for newly arrived inmates, is crowded with nearly twice the 900 prisoners it was meant to hold, according to state figures.
Stress is high and assaults are up at the prison, said Tim Shafer, an official with the guards' union, who added: "Just like out in the public, suicides happen, and you just can't prevent every one of them."
More Nation & World Headlines
Analysis: Can Donald Trump be stopped? Refugee surge to Europe raises concern about militants Hungary declares emergency, seals border, detains migrants 4:17 p.m. 3 dead, 4 missing in Zion National Park after flash flooding 4:19 p.m. N. Korea warns it has restarted all nuclear bomb fuel plants Searchers look for flood victims in polygamous Utah town 4:16 p.m. Value of anti-IS airstrikes in Syria debated as France joins Things to watch in Wednesday’s Republican debate
Our new comment system is not supported in IE 7. Please upgrade your browser here.