The accused have been handed over at the border village of Panmunjom in the demilitarized zone that separates North and South. The men had indicated a willingness to defect, but their statements to police didn't add up.
South Korea deported two North Koreans accused of murdering 16 fellow fishermen on Thursday after the pair had fled south from their homeland.
The two men were found on Saturday near the maritime border in the East Sea.
Having been discovered in the stretch of water also known as the Sea of Japan, they were then brought in for questioning.
The authorities subsequently concluded that the men, who are both in their 20s, had fled to the South after killing 16 of their colleagues on board the boat, Seoul's Unification Ministry spokesman Lee Sang-min (pictured top) told reporters.
The suspects were extradited via the truce village of Panmunjom after Seoul briefed North Korea of their decision.
"The government decided to expel them as they had committed grave, non-political crimes such as murder and were not subject to our protection under the law," ministry spokesman Lee said.
"We also assessed that if they were accepted into our society, they would pose danger to our people's lives and safety as vicious criminals who cannot be recognized as refugees under international law."
jsi/rt (AP, AFP, Reuters)