An American university student who was detained for 17 months in North Korea and suffered a serious neurological injury was "brutalized" while in custody, his father said on Thursday.
Doctors will provide further details about Warmbier's condition on Thursday afternoon.
Warmbier has been in a coma since March 2016, shortly after he was sentenced to 15 years of hard labor in North Korea, the family said on Tuesday after he was released.
He was arrested for trying to steal an item with a propaganda slogan, North Korean media reported.
The University of Virginia student was "brutalized and terrorized" by the North Korean regime, his father Fred Warmbier said at the news conference two days after his son was returned.
North Korea's official KCNA news agency said in a one-line report on Thursday the student was sent home "on humanitarian grounds."
Fred Warmbier said the family did not believe North Korea's story, that his son had fallen into a coma after contracting botulism and being given a sleeping pill.
"We don't believe anything they (North Korea) say," said Fred Warmbier, who was wearing a sport coat Otto Warmbier had worn during a broadcast confession of his crimes last year in North Korea.
The New York Times previously cited a senior U.S. official as saying Washington had received intelligence reports Warmbier was repeatedly beaten while in captivity.
Fred Warmbier said he was stunned when told of his son's condition one week ago.
"I don't know what being in shock is, but I'm pretty sure I was," Fred Warmbier said, referring to being informed Otto Warmbier was in a coma.
"There is no excuse for any civilized nation to have kept his condition secret and denied him top-notch medical care for so long," he added.
He said his wife, Cindy, had not left their son's side since his return to the United States.
Blue and white ribbons, representing the colors of the high school, were tied around trees and telephone polls throughout Wyoming, a northern Cincinnati suburb of about 8,000 people.
Fred Warmbier said of his son's release by the regime: "They did not do this out of the kindness of their hearts."
U.S. President Donald Trump spoke to Fred Warmbier on Wednesday night, Warmbier said. Trump discussed how U.S. Secretary of State Rex Tillerson and Joseph Yun, the U.S. State Department's special envoy on North Korea, worked together to help secure Otto's release, Warmbier said.