And Yun was dispatched to North Korea and visited Warmbier with two doctors on Monday, and demanded his release.
The Warmbier family said they were informed that North Korean officials had told American envoys that their son became ill with botulism soon after his show trial in March previous year.
Rodman has received the red-carpet treatment on four past trips since 2013, which have accomplished little in terms of diplomacy and served mainly to create publicity for the former athlete. Richardson has played a role in past negotiations with North Korea.
Authorities are believed to have arrested Kim Hak Song, who had been in North Korea for several weeks working at the Pyongyang University of Science and Technology (PUST), on May 6 this year as he was about to leave the country.
Warmbier's parents said in a statement to The Associated Press that they had learned only a week ago that their son has been in a coma since March 2016. North Korea sentenced Warmbier to prison after he admitted trying to steal a propaganda banner during a trip there.
The Warmbier family released a statement Tuesday saying they are grateful their son will finally be home with the people who love him.
The father of an American college student who was imprisoned in North Korea and was returned to his home state of OH in a coma says the family is "adjusting to a different reality.". Of Otto's parents, Cynthia and Fred Warmbier, he said: 'I can't even begin to put myself in their shoes'. Let me reiterate this: "We strongly, strongly suggest that Americans do not go to North Korea". "He grew up here, people know him well, we wish him the very best and we wish him a full recovery", McCauley said.
In Warmbier's hometown of Wyoming, just outside of Cincinnati, residents helped tie blue and white ribbons, Wyoming High School's colors, to trees and said news of his release had sent waves of shock and joy through the community. President Donald Trump has been promising to exert "maximum pressure" on North Korea to make it abandon its nuclear weapons program, but has also dangled the prospect of talks with Kim, whom he called a "smart cookie". The official referred to them as "hostages".
Doctor: Scalise improving, came in at 'imminent risk of death'
The hospital said earlier in the week that he had undergone surgery for internal injuries and a broken leg. President Donald Trump said Friday that Steve Scalise "took a bullet for all of us".
The U.S. government condemned the sentence and accused North Korea of using such American detainees as political pawns. North Korea accuses Washington and South Korea of sending spies to overthrow its government.
Three U.S. nationals are still being held in the DPRK following Warmbier's release.
Three other Americans remain in North Korean jails.
Asked whether he had spoken with Trump about his trip, Rodman said: "I'm pretty sure he's pretty much happy with the fact that I'm over here trying to accomplish something that we both need".
Since taking office in January, Trump has faced a growing national security challenge from North Korea, which has conducted a series of ballistic missile tests in defiance of USA and global sanctions.
He said in Beijing his aim is to try to "bring sports to North Korea".
North Korea will top the agenda at next week's high-level talks between U.S. and Chinese officials, he added. A 2009 visit by former President Bill Clinton secured the freedom of American journalists Euna Lee and Laura Ling.
A ministry official explained on Wednesday that Seoul and Washington have been in close consultations over the issue of American citizens detained in the North, adding the ministry has no further comment on the matter outside of the U.S.' announcement on the release of Otto Warmbier.