SEOUL: South Korean President Moon Jae-in on Tuesday said North Korea should swiftly return South Koreans and Americans detained in the reclusive nation and that it had “a heavy responsibility” in the death of a US university student. Otto Warmbier, the 22-year-old student who had been held prisoner in North Korea for 17 months, died at a Cincinnati hospital on Monday just days after North Korea released him from captivity in a coma, his family said. Three other US citizens, who are ethnic Koreans, and six South Koreans remain in custody in North Korea. Warmbier was arrested while visiting as a tourist and accused of trying to steal an item bearing a propaganda slogan, according to North Korean media. Doctors caring for him last week described him as having extensive brain damage that left him in a state of “unresponsive wakefulness.”In an interview with CBS News, Moon said that while “we cannot know for sure that North Korea killed Mr. Warmbier … I believe it is quite clear that they have a heavy responsibility in the process that led to Mr. Warmbier’s death.”