An Ohio coroner who performed an external examination on Otto Warmbier’s body has said she found no obvious signs of torture, despite claims the University of Virginia student was tortured by North Korean authorities. At a news conference in Ohio on Wednesday, Hamilton County Coroner Lakshmi Sammarco said Warmbier, who was returned to the U.S. in a coma in June after 17 months in custody, died from a lack of oxygen and blood to the brain. She said she could not determine what caused such a neurological condition, however. Warmbier’s parents had said a day earlier that their son was clearly tortured while in North Korea, with his teeth “rearranged” and his hands and feet disfigured. Sammarco, who did not perform a full autopsy on Warmbier’s body, said Wednesday she did not see any signs of broken bones or trauma to his teeth. “We don’t know what happened to him and that’s the bottom line,” she said.