CINCINNATI -- The Hamilton County Coroner said on Wednesday her office did not see "any evidence of trauma" to Otto Warmbier's teeth upon his return from North Korea.

Fred Warmbier, Otto's father, said "it looked like someone had taken pliers and tried to rearrange his bottom teeth" when he described the state the 22-year-old was in when he returned to the U.S. in June.

"He was on a stretcher, jerking violently, making this howling, involuntary, inhuman sound," Fred Warmbier said. "His head was shaved, he had a feeding tube in his nose. He was blind, he was deaf. As we looked at him and tried to comfort him, it looked like someone had taken pliers and tried to rearrange his bottom teeth. He reached a 104 degree fever and he had a large scar on his right foot."

Fred and Cindy Warmbier were on Fox & Friends Tuesday morning and CNN Tuesday afternoon for their first interviews since their son's funeral in June.

Dr. Lakshmi Sammarco said she was surprised by the Warmbier's statement.

Sammarco’s office performed an external examination, went through extensive medical imaging and conducted a post-mortem CT scan of Warmbier’s body.

A forensic dentist examined the images, specifically the lower teeth and mandible, Sammarco said.

“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.

Doctors described Warmbier's condition as a state of "unresponsive wakefulness" after they examined him upon his return from North Korea.

Dr. Daniel Kanter, director of Neurocritical Care Program at the University of Cincinnati Medical Center, said his coma was likely caused from cardiac or respiratory arrest, which decreases blood supply and results in the death of brain tissue.

Dr. Jordan Bonomo said respiratory arrest is the main cause of cardiopulmonary arrest in a young person, and respiratory arrest is typically caused by “intoxication or traumatic injury.”

“We do see respiratory arrests from overdose -- from medication overdose -- intentional or otherwise,” Bonomo said. “It would be inappropriate for me to speculate about the intent or whether this was a misadministration of a medication.”

Doctors found no evidence of trauma after examining all of Warmbier's bones. Kanter said scans did not show any acute or healing fractures, including scans of his skull.

Earlier reports of Warmbier’s condition stated North Korean officials claimed he had contracted botulism, and he fell into a coma after he was given a sleeping pill.

Dr. Brandon Foreman, associate director for Neurocritical Care Research, said there was no evidence that would suggest “active or chronic” botulism -- a nerve-damaging bacteria.

Kanter said there is no way to tell for certain how Warmbier sustained his injuries. Kanter also said Otto's "skin was in good condition, and he was well-nourished when he arrived at our facility."