Story highlights Warmbier was imprisoned in January 2016

Source close to his family says he's in "bad shape"

Washington (CNN) New details are emerging about US efforts to secure the release of American college student Otto Warmbier after more than 17 months in detention in North Korea.

The 22-year-old contracted botulism and is in "bad shape" but en route back to the United States, a source close to the family told CNN on Tuesday.

The diplomatic process began on June 6 when State Department Special Representative Joseph Yun met with North Korean UN Mission Ambassador Pak Kil-yon in New York City and learned of Warmbier's deteriorating health condition, according to a senior State Department official.

After that meeting in New York, Secretary of State Rex Tillerson consulted with President Donald Trump and instructed Yun to prepare to travel to North Korea with the intent of bringing Warmbier back to the United States, the official told CNN.

A US delegation made up of Yun and a medical team was sent to North Korea on Monday to secure Warmbier's release, the official said, adding that they demanded to visit Warmbier upon arrival in Pyongyang.

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