Convicted Cleveland kidnapper Ariel Castro was found dead in his Ohio prison cell Wednesday morning.

He committed suicide, authorities say.

Castro, 53, was in protective custody and was checked every 30 minutes. He had hanged himself.

Last month, Castro was sentenced to life in prison plus 1,000 years with no parole for abducting, raping and holding captive three women, and murder for forcing one of the women to abort her pregnancy.

He admitted he kept the three women in his basement for more than a decade.  He pleaded guilty to 937 charges, including rape, kidnapping and assault.

Michelle Knight, 32, Amanda Berry, 27, and Gina DeJesus, 23, all went missing in Cleveland between 2002 and 2004.

They were discovered in May after neighbours heard Berry’s cries for help from Castro’s home.

With files from CNN and Reuters