Although North Korea is one of the most isolated countries on the planet, it has been trying to encourage tourism in recent years, and a handful of companies regularly take groups there without incident.

The State Department, however, has steadily ratcheted up its travel warning for North Korea, noting the risk of arbitrary detention. The United States has no diplomatic relations with Pyongyang and is represented there by the Swedish Embassy.

On Otto’s final night in Pyongyang, New Year’s Eve, he appears to have gone to a staff-only floor of his hotel and attempted to take down a large propaganda sign lauding the regime.

He was charged with “hostile acts against the state” and after an hour-long trial in March, sentenced to 15 years in prison with hard labor. That was the last time Otto was seen in public, and Swedish diplomats have been denied access to him since then.

In the absence of other information about him, some quarters of the Internet have been less than sympathetic to Otto. But he is not some reckless kid who went to North Korea on a lark, his parents say.