(CNN) -- Convicted kidnapper Ariel Castro killed himself, the Ohio medical examiner who conducted his autopsy says, disputing assertions that the convicted kidnapper and rapist may have died accidentally.
Coroner Jan Gorniak had harsh words for Ohio corrections officials for raising the possibility in a report Thursday that Castro's death may have been the accidental result of auto-erotic asphyxiation. That involves depriving the brain of oxygen by controlled strangulation to intensify a sexual experience.
"I did the autopsy myself. I saw the ligature. I saw the pictures of the cell," she said. "It was a suicide."
The state report released Thursday, meanwhile, also found that prison guards falsified logs and did not check on Castro as often as they should have. They appeared to have also falsified "the post log book for their rounds," according to the report, from the Ohio Department of Rehabilitation and Correction.
The guards were placed on leave as authorities looked into Castro's death. Investigators have not decided on whether to take any disciplinary action.
As for the report's mention of the possibility that Castro's death was accidental, the coroner said no one involved in the report consulted her -- and she's not happy about that.
"They were outside of their lane ... I don't think anyone else should have an opinion on what the cause of death was," Gorniak said.
In its report, the Ohio Department of Rehabilitation and Correction noted that Casto's body was found hanging from a sheet wrapped around his neck and tied to a hinge in the window of his cell.
"His pants and underwear were pulled down to his ankles," the report said. "The relevance of this finding is unclear. These facts, however, were relayed to the Ohio State Highway Patrol for consideration of the possibility of auto-erotic asphyxiation."
Gorniak said she was not made aware that Castro was found with his pants down in the jail cell, but that does not change the cause of death. There were no signs that he was sexually stimulated, she said. And his pants may have slipped off while he was hanging, she said. He left no suicide note, the report said, but not everyone who commits suicide does, the coroner said.
Castro was imprisoned for more than 1,000 years for kidnapping and raping three women who he held in captive in his Cleveland home for years. He was found dead in his jail cell on September 3.
Meanwhile, the report released Thursday also said that two prison guards responsible for checking on Castro "did not timely perform" required rounds.