Ariel Castro, 53, committed suicide in his Ohio prison cell on Tuesday.

CLEVELAND — Ohio’s prison system is reviewing how Cleveland kidnapper Ariel Castro — perhaps the most notorious figure behind bars in the state — managed to hang himself with a bedsheet while in protective custody.

Castro was a month into his life sentence for holding three women captive in his home for a decade when he committed suicide Tuesday night. Protective custody involves checks every 30 minutes.

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 also are 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 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.

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.