(SEOUL, South Korea) — In an extremely unusual case, South Korea deported two North Korean fishermen on Thursday after finding they had killed 16 other crew members on their boat and then fled to South Korean waters, Seoul officials said.

The two North Koreans, both men in their 20s, were captured in their boat south of the countries’ eastern sea border last Saturday, according to Seoul’s Unification Ministry. It said a South Korean investigation later found the two had killed 16 colleagues, including the captain.

South Korea has a policy of accepting North Koreans who want to resettle in the South to avoid political oppressions and economic poverty at home. It is the first time that South Korea has deported any North Korean national who has come to South Korea since the end of the 1950-53 Korean War, according to the Unification Ministry, which deals with North Korean affairs.

Ministry spokesman Lee Sang-min said South Korea decided to expel the two fishermen to North Korea because they were “heinous criminals” who could not be recognized as refugees under international laws. Lee said the two were sent back through the Koreas’ land border.

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