Otto Warmbier, a U.S. university student held captive in North Korea for 17 months, has been released, but a former U.S. official said on Tuesday he is in a coma and in urgent need of medical care.

Mr. Warmbier, 22, a University of Virginia student from suburban Cincinnati, was on his way back to the United States, Secretary of State Rex Tillerson said in a statement.

He has been in a coma for over a year now and urgently needs proper medical care in the U.S., said Bill Richardson, a veteran former diplomat and politician who has played a role in past negotiations with North Korea, said after speaking to Mr. Warmbier’s parents.

Ill from botulism

The family said they were told by North Korean officials, through contacts with American envoys, that Mr. Warmbier fell ill from botulism sometime after his March 2016 trial and lapsed into a coma after taking a sleeping pill, the Washington Post reported.

In no uncertain terms North Korea must explain the causes of his coma, Mr. Richardson, whose Center for Global Engagement had directly sought Mr. Warmbier’s release with the North Korean government, said.

Mr. Tillerson, at a U.S. Senate hearing on Tuesday, declined to comment on Mr. Warmbier’s condition.

Mr. Warmbier’s release came as former U.S. basketball star Dennis Rodman arrived in North Korea on Tuesday, returning to the increasingly isolated nuclear-armed country where he has previously met leader Kim Jong-un.