North Korea on Friday sent home a South Korean man who had crossed illegally into the impoverished communist state in an apparent attempt to defect.
Ma Sang-Ho, 52, was repatriated through the border village of Panmunjom and held by the South's security authorities for questioning, Seoul's unification ministry said.
Ma had wanted to live in the North, claiming he was treated in the South as "a mentally deranged person," according to an earlier statement by the North's Red Cross.
It was not clear why Pyongyang had rejected his request.
More than 26,000 North Koreans have escaped to the South since the end of the Korean War in 1953, but defections in the opposite direction are very rare.
The few defectors that Pyongyang does receive have usually been allowed to stay in the secretive state.
However, last year Pyongyang sent home six South Koreans who had entered the North illegally between 2009 and 2012. In September this year, a man was repatriated after he crossed illegally into the North through China.
The North has rejected Seoul's repeated calls to free a South Korean missionary who was captured last year and sentenced to life in a labour camp for allegedly spying and operating an underground church.
The North views foreign missionaries as seditious elements intent on fomenting unrest.