This morning came word suddenly that the United States had secured his release, but under apparently desperate circumstances.
Warmbier said before his trial that he tried to steal the propaganda poster as a trophy for an acquaintance, who offered him a used vehicle worth $13,200 in exchange for the item.
Warmbier's parents, Fred and Cindy Warmbier, said they were told he has been in a coma since his trial, when he was last seen in public, and they had learned of this only one week ago.
Imprisoned in North Korea are three of a United States citizen.
ANNA FIFIELD: Once Otto Warmbier's condition was known, I'm told that the president did become involved, that he was informed, that he personally gave the order to do everything that they could to get Otto Warmbier out. "At the moment, we're just treating this like he's been in an accident".
The Warmbiers have been relentlessly pressing - first behind the scenes and then more publicly - for their son's release.
He was given a sleeping pill after becoming ill after his trial past year and did not wake up, North Korea said. He has never woken up since. A few months later, he made another visit with a group of former National Basketball Association players.
Tillerson told USA senators at the start of a budget hearing that the State Department had no comment on Warmbier's condition "out of respect for him and his family".
Tillerson said the State Department is still working to secure the release of three other US citizens detained in North Korea.
A senior U.S. official said they had received worrying reports on his condition in a North Korean gulag, which prompted talks to bring him home immediately. No further details were provided. He visited Warmbier with two doctors on Monday, and demanded his release on humanitarian grounds.
Some analysts speculated that Rodman may even be carrying a message from President Donald Trump, who previously had praised Rodman's efforts to engage North Korea.
The young undergraduate honors student was forced the next month, at a staged news conference, to admit to a "very severe and pre-planned crime", saying that the "aim of my task was to harm the motivation and work ethic of the Korean people".
A White House official says the May meeting in Oslo was attended by Joseph Yun, the US envoy to North Korea.
Mr Warmbier allegedly attempted to steal a propaganda banner from the hotel in which he was staying, but it remains unclear whether this is true.
Otto Warmbier (WORM'-bir), who had been serving a 15-year prison term, was freed and evacuated from North Korea on Tuesday, as Rodman arrived in the reclusive country. He also suggested that Obama simply pick up the phone and call the North Korean leader. He'd been in custody since January 2016 and was sentenced in March 2016 in a one-hour trial.
Mr Warmbier said he accepted the offer as his family was "suffering from very severe financial difficulties".
He was given a sleeping pill and had been in a coma ever since, the newspaper said. The magazine of the university's alumni association describes the Z Society as a "semi-secret ring society" founded in 1892 that conducts philanthropy, puts on honorary dinners and grants academic awards.
While traveling in Tokyo, Thomas Shannon Jr., the USA undersecretary of state for political affairs, said Rodman was not acting in any official capacity.