Otto was in a coma when N. Korea set him free last week. He'd been at the University of Cincinnati Medical Center since then. He was surrounded by family when he passed away ... according to a statement from the Warmbiers.

The family said, "Unfortunately, the awful torturous mistreatment our son received at the hands of the North Koreans ensured that no other outcome was possible beyond the sad one we experienced today."

Otto, a University of Virginia student, had been sentenced to 15 years in prison last year after he allegedly tried to take down a political propaganda sign in Pyongyang. N. Korean officials claim he contracted botulism, and after they gave him a sleeping pill ... he never woke up.

Otto was 22.

President Trump said, "Melania and I offer our deepest condolences to the family of Otto Warmbier on his untimely passing. Otto’s fate deepens my Administration’s determination to prevent such tragedies from befalling innocent people at the hands of regimes that do not respect the rule of law or basic human decency."