The prognosis doesn't look good for freed North Korean detainee Otto Warmbier.

At a Thursday afternoon press conference, doctors at the University of Cincinnati Medical Center revealed that much of the 22-year-old's brain has died, leaving him without the ability to speak, understand language or even move - besides the occasional fluttering of his eyelids.

The doctors appeared to refute the North Korean regime's account that Warmbier went into a coma after getting botulism a day after he was sentenced to 15 years of hard labor for stealing a poster during a visit to the hermit state.

Dr. Brandon Foreman said he ran tests that showed no signs of botulinum poisoning, an issue usually caused by eating improperly home-canned foods.

While Warmbier's condition did not look positive, doctors refused to say whether he had a chance of recovering, saying the family wanted privacy on the matter.

The medical team spoke hours after Warmbier's father Fred spoke at a different press conference - condemning the North Koreans for what they had done to his son.

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Dr Daniel Kanter of the University of Cincinnati Medical Center speaks at an afternoon press conference about patient Otto Warmbier

Dr Kanter and his colleagues refused to give a prognosis, saying that Warmbier's family wanted privacy

Dr. Brandon Foreman said Warmbier shows no signs of awareness and that tests showed he doesn't have botulism, as the North Korean regime has claimed

As soon as he arrived in the U.S. by medical transport plane Tuesday night, Warmbier was rushed to the hospital.

Doctors said he was in a stable condition when he arrived and has remained stable.He has showed no need for supplementary oxygen or a respiratory machine, and has no infections.

However, he also hasn't shown a sign that he is at all aware of what is going on around him.

He hasn't spoken and he doesn't seem to understand people talking to him, nor has he responded to any other stimulus. They described Warmbier as being in a state of 'unresponsive wakefulness'.

A scan of his brain showed that Warmbier has suffered an 'extensive' loss of tissue from 'all regions of the brain'.

They say the tissue loss is consistent with an event that caused a lack of oxygen flow to the brain.

The doctors said they believed Warmbier suffered cardio-pulmonary arrest - in other words, a heart attack.

For a young person who is otherwise healthy, heart attacks can be triggered by suffering trauma, or some kind of intoxication - such as an overdose.

However, the doctors refused to speculate on what specifically may have caused Warmbier to suffer a heart attack while in North Korean hands.

The North Koreans sent a disc on the plane with two previous MRI scans dated April and July 2016.

It is the current medical team's opinion that he suffered the brain injury in the weeks preceding the first scan.

They have not been in contact with the North Korean medical professionals who took care of Warmbier before he was released, sothey could not comment on how he was treated.

But they said his body showed no signs of physical abuse, such as broken bones or bruises

Fred Warmbier, the father of freed North Korean prisoner Otto Warmbier, spoke at an earlier press conference, wearing the same jacket that his son wore when he was sentenced to 15 years of hard labor for stealing a poster during a trip to North Korea

State Department officials helped secure the 22-year-old's release this week after a 17-month detainment in North Korea for stealing a poster.

Right before he was flown back to the U.S., the regime revealed he had been in a coma due to botulism since the day after he was sentenced to 15 years of hard labor in March 2016.

At the same press conference, held at Otto's former high school in Wyoming, Ohio, his father Fred called what the North Koreans did to his son unconscionable, while blaming President Obama for not doing enough to secure his son's release.

'Even if you believe their explanation of botulism and a sleeping pill - and we don't - there is no excuse for any civilized nation to have kept his condition secret and denied him top-notch medical care for so long,' Mr. Warmbier said, while wearing the same jacket that his son wore to his sentencing in North Korea.

He added that the North Koreans have proven that they are 'not nature's noble men'.

There's no excuse for the way the North Koreans treated our son and the way they have treated so many others. Fred Warmbier, father of Otto Warmbier

'There's no excuse for the way the North Koreans treated our son and the way they have treated so many others,' Mr Warmbier said.

He called on the regime to release the other foreigners being held against their well, saying 'no other family should have to endure what the Warmbiers have'.

'We have been brutalized for the past 18 months with misinformation and no information,' Mr Warmbier said. 'We're just thrilled that he is on American soil.'

Mr Warmbier, the president of a specialty chemical company, also expressed his family's frustrations at the Obama Administration's efforts - or lack there of - to get his son back when he was first held by the North Koreans more than a year ago.

He said the family was 'advised by the past administration to take a low profile while they worked to get his release'.

But Mr Warmbier said that tactic didn't work, so they decided to go public with their son's story earlier this year when President Trump came into office.

'We went public with an interview on the Tucker Carlson show, did a couple of written pieces and very quickly we have Otto home,' he said.

When asked by a reporter if he thought the Obama administration didn't do enough to bring Otto home, Mr Warmbier responded 'I think the results speak for themselves'.

Mr Warmbier got emotional throughout the interview as he talked about his hospital-bound son

Mr Warmbier thanked the Trump administration for helping secure his son's release

He also said that Mr Obama never met with the family once in a face-to-face meeting - despite more than a dozen trips to Washington, DC to speak with then Secretary of State John Kerry, lawmakers and other dignitaries.

'Oh, never never. Absolutely not, no,' he said.

President Trump on the other hand, called Mr Warmbier last night to see how they were doing following Otto's return.

He said the president asked 'how [my wife] Cindy and I were doing. He wanted to know about Otto. It was a really nice conversation'.

'To be honest, I avoided conversations with him because...to what end? This is about Otto. But I took the call and it was gracious, it felt good and I thank him for that,' Mr Warmbier said.

To be honest, I avoided conversations with [President Trump] because...to what end? This is about Otto. But I took the call and it was gracious, it felt good and I think him for that. Fred Warmbier

The regime claimed he had been promised a $10,000 used car by a church in Wyoming, a wealthy northern suburb of Cincinnati. But Fred Warmbier ridiculed that suggestion.

'Does it look like my son needs a used car?' asked Warmbier. 'He isn't even a member of that church.'

A grainy video, allegedly showing Warmbier removing the poster which read 'Let's arm ourselves strongly with Kim Jong-il's patriotism!' was shown at the trial, but the person's face was hidden so there was no proof that it was actually him. Kim Jong-il was the father of current leader Kim Jong-un.

Warmbier also attacked the China-based company Young Pioneer Tours that organized his son's trip to the hermit kingdom. He said the company helps Kim's regime 'lure' Americans to North Korea.

Warmbier arrived back in Lunken regional airport in Cincinnati Tuesday night on board a military aircraft following his release from custody by North Korean authorities

Ottos was rushed to the University of Cincinnati Medical Center after being carried off a plane, but no update on his condition has been released

'My son happened to become fodder for the North Koreans,' he said. 'They took him hostage at the airport,' he said.

'Otto's a young, thrill-seeking, great kid who was going to be in that part of the world for a college experience and said he would like to do this, so we agreed to let him do that.

'They lure Americans and then they take them hostage and then they do things to them — and that is what happened to my son.

Mr Warmbier's wife Cindy decided to skip the press conference, choosing instead to stay by her son's side.

But her husband read a statement, saying that she knows their son 'is a fighter' and that they 'firmly believe that he fought to stay alive through the worst that they put him through in order to return to the family and the community he loves'.

He said it was a 'bittersweet feeling' having their son home.

There's 'relief that Otto is now home in the arms of those who love him and anger that he was so brutally treated for so long'.

Mr Warmbier also described the moment that he met his son at the airport Tuesday night.

'I knelt down by his side and I hugged him and I said I missed him and that we're so glad he made it home,' Mr Warmbier recalled.

Fred Warmbier said hat his son was 'terrorized and brutalized' during his 17-month detention

The family's many priority now is making Otto comfortable, Mr Warmbier said.

He went on to describe his son as a 'sweet, loving, kind person' who always made him look good as a father for his many achievements in school.

'We went for 15 months without a word from or about Otto. It was only a week ago that we were informed that the North Korean government now claims he was in a coma for almost all of that time.

'We have few answers,' said Warmbier.

'The brutality he endured and the terror that he went through and the performance he gave doesn't really speak to who Otto is.

He said the first thing he did when he saw Otto back on American soil was to kneel by his side and hug him. 'I told him I missed him and I was so glad he had made it home. We are trying to make him comfortable and want to be part of his life.

'I'm proud of Otto and the courage he showed by going to North Korea and having that adventurous side to him.

When asked by a reporter if he thinks Dennis Rodman had anything to do with his son's release, he said no.

The former NBA star has befriended North Korean leader Kim Jong-un, and flew to North Korea just as Otto was being released.

'Dennis Rodman had nothing to do with Otto. It's a diversion. I'm sure this is all planned,' he said.

When asked if he had been following Rodman's trip, Mr Warmbier said 'I could care less'.

Mr Warmbier has also sat down for an interview with Tucker Carlson, which is set to air in full Thursday night at 8pm.

Carlson previewed the interview Thursday morning, posting a clip in which Mr Warmbier said his son had been 'terrorized and brutalized' by the North Koreans.

He said the family is now 'adjusting to a different reality' now that their son is home, albeit with a severe medical condition.

Fred Warmbier says that his family is 'adjusting to a different reality' after his son Otto was released by the North Korean regime in a coma

The 22-year-old University of Virginia student was medically evacuated from North Korea and arrived in Cincinnati late Tuesday. He was then taken by ambulance to the University of Cincinnati Medical Center.

Residents of the northern Cincinnati suburb tied blue-and-white ribbons, the school colors, to trees near the family's home. Joy at his release was mixed with concern over his condition.

In its first official comment since Warmbier was returned home, North Korea said it released him over humanitarian reasons. The state-run Korean Central News Agency on Thursday said he had been sentenced to hard labor but did not comment on his medical condition.

Above, a family member wipes away tears after seeing Otto taken off the plane hooked up to life support on Tuesday

Well wishers stood at the edge of the airport to welcome home the student

Former New Mexico Gov. Bill Richardson, a former U.S. ambassador to the United Nations, said there should be an investigation into what happened to Warmbier leading to this 'tragic situation.'

Richardson, a Democrat, credited the Department of State with securing Warmbier's return from North Korea without any preconditions but said a forceful response from the U.S. government would be required 'if its determined that there was a cover-up and Otto's condition was not disclosed and he didn't get proper treatment.'

City councilwoman Jenni McCauley said the tight-knit community was 'thrilled' to have Warmbier back.

'Even though they're saddened by his condition, they're just glad for the family that he is home,' McCauley said. 'For any parent, this is their worst nightmare. ... We're hoping that he will be OK.'

Cindy Warmbier (right, with her husband) skipped the Thursday morning press conference to stay by her son's side

Warmbier was serving a 15-year prison term with hard labor in North Korea after he tearfully confessed that he tried to steal a propaganda banner while visiting the country.

Such detentions in the totalitarian nation have added to tensions between Washington and Pyongyang. Three Americans remain in custody.

The U.S. government accuses North Korea of using such detainees as political pawns. North Korea accuses Washington and South Korea of sending spies to overthrow its government.

Secretary of State Rex Tillerson said Tuesday that his department was continuing 'to have discussions' with North Korea about the release of the other three imprisoned American citizens.

When asked by Fox News what he would tell the families of those detained, Fred Warmbier said, 'I wouldn't know what to say to them. This is, I've been told, not precedented.'