Two sheets of paper were found in the cell, one with Bible verses written on it and the other with the names of Castro's children and grandchildren, the notes said. A Bible open to the book of John was also found.
Franklin County Coroner Jan Gorniak said she's awaiting toxicology results before issuing a final report on Castro's Sept. 3 suicide. The preliminary notes indicate he suffered from hardening of the arteries.
Cleveland's WKYC-TV first reported details of the notes.
Castro was found at 9:20 p.m. the night of the suicide, about 30 minutes after he was last seen alive, according to the notes. He was pronounced dead at a hospital an hour and a half later.
Castro, 53, pleaded guilty last month to nearly 1,000 counts related to his imprisonment of three women in his Cleveland home for a decade, including aggravated murder — for forcing one of the victims to miscarry — kidnapping, rape and other crimes.
Castro kidnapped the women between 2002 and 2004 when they were 14, 16 and 20 years old. He housed them in brutal conditions, restricting access to food and toilet facilities, chaining them and beating them repeatedly. He fathered a girl with one of the victims.
One of the women escaped May 6 and alerted authorities, at first bringing joy to the city where they had become household names after years of searches and vigils, then despair as details of their treatment emerged.
Castro was four weeks into a sentence of life without parole plus 1,000 years when he killed himself. His body was released to his son in Columbus.
Castro's suicide is the subject of three prison reviews. Two, looking at the circumstances of his death and at mental and medical health treatment he received beforehand, are due at month's end.
A third review is being done by two nationally known prison conditions experts. That review, announced this week, also examines the Aug. 4 suicide of death row inmate Billy Slagle three days before his scheduled execution.
The study, due Nov. 15, will also examine prison suicides over the past two years and make recommendations for any changes to the state's policies and procedures for stopping inmates from killing themselves.