The New York University student repatriated from North Korea earlier this week is currently under investigation for violating South Korea’s National Security Act, South Korean media have reported.

Because Joo, 21, entered into North Korea without permission and made pro-North remarks during an interview in North Korea, he appears to have violated the law, which South Korea has had on the books since the late 1940s.

“I would like to say that I’m well and there’s no need to worry because the people here have treated me with the best of humanitarian treatment,” Joo told CNN in May.

Lawyers said