North Korea previously blamed botulism and the ingestion of a sleeping pill for Mr Warmbier's condition, and dismissed torture claims.
Mr Warmbier's body had multiple scars varying in size, including a large irregular one measuring 11 centimetres by 4 centimetres on the right foot, the report said. The manner of death was undetermined, but Sammarco said it could have happened naturally had he undergone cardiac arrest.
Otto Warmbier's father says they wanted to speak out after hearing North Korea claiming to be a victim. "As we looked at him and tried to comfort him, it looked as if somebody had taken a pair of pliers and rearranged his bottom teeth".
About three months ago, Otto Warmbier passed away just a few days after he returned to the US.
"They destroyed him", Cindy Warmbier said. When he returned to the U.S., his parents discovered that he had been in a coma for over a year.
"He agreed with us that there was no evidence of trauma to the lower teeth or mandible on the imaging or by physical examination", Sammarco said.
The Warmbiers said they had made a decision to speak out now partly because they were aghast at efforts by the North Korean government to portray itself as the victim of USA aggression in the unfolding crisis over the North's nuclear weapons and missile testing. However, the coroner's office found a scar that "we really couldn't explain through medical instrumentation", Sammarco said.More news: Man United focused on winning Champions League — Henrikh Mkhitaryan
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Otto had been arrested and sentenced to 15 years hard labour after travelling to North Korea in January 2016 and allegedly stealing a propaganda poster.
His post followed the airing of an interview with Warmbier's parents.
Doctors said the most important diagnostic test was a brain scan that showed "extensive loss of brain tissue in all regions of the brain", but admitted they had no certainty about how it occurred. "They kidnapped Otto, they tortured him, they intentionally injured him".
A coroner's report gives a cause of death for a young Ohioan detained for more than a year by North Korea, but couldn't determine what led to his fatal brain damage.
After a medical team boarded the plane that carried Otto back to the US, his family was allowed to see him.
The parents on Tuesday, for the first time, described publicly in detail the condition his family found him in when they went aboard an air ambulance that arrived June 13 in Cincinnati.
The Hamilton County coroner has scheduled a news conference to discuss a newly released report on the examination of the body of a college student from OH who was held more than a year and died less than a week after his release from North Korea.