The case of the two fishermen was also unusual because it marked the first in which South Korea rejected North Korean defectors because of their alleged crimes in the North or because their intent to defect was considered disingenuous.

In a joint statement this week, Human Rights Watch and 66 other rights groups ​accused ​​South Korea ​of failing in its obligation under international treaties to “protect anyone who would be at substantial risk of torture or other serious human rights violations after repatriation.”

​Few personal details have been revealed about the two North Korean​s, except that one was the boatswain and the other a deck hand. Their fateful journey began on Aug. 15, when their 17-ton wooden boat with 19 men on board cast off from Kimchaek​ on the east coast of North Korea, South Korean​ officials said.

The two​, together with the ship’s chief engineer, mutinied against the captain’s abuse ​on a late October​ night​, killing him with hammers and axes. They then went on a killing spree to hide their crime. They awakened the​ir ​colleagues two at a time, lured them outside and butchered them, throwing their bodies overboard.

They steered their ship back to Kimchaek, hoping to sell the squid and flee inland​. When the engineer was arrested by the Kimchaek​ police​, the other two fled back to the sea.

By the time their boat ​approached the inter-Korean sea border on Oct. 31, the South Korean authorities said they had picked up intelligence that ​North Korea was looking for ​them. South Korean patrol boats fired​ warning shots and broadcast warnings, a standard procedure when a North Korean fishing boat crosses the border without signaling that those on the boat are defecting​.

The boat repeatedly crossed back and forth across the maritime border for two days, until South Korean Navy commandoes ​finally ​seized ​it on Nov. 2.​ Both men quickly confessed to mass murder, providing identical details of the​ crime during separate interrogations, South Korean officials said. They then said they wanted to defect to the South​.