SEOUL — The scandal exploding today in South Korea over the decision of the previous president to return two defectors to certain death in North Korea is illuminating a bigger question — the efforts of the former president, left-winger Moon Jae-in, to appease the North.

The powerful National Intelligence Service charges that a previous NIS director, Suh Hoon, halted the investigation into the case of the two defectors, who were forcibly handed over to the North Koreans at the truce village of Panmunjom in November 2019.

The North alleges that the two defectors had killed 16 others on their fishing boat before it was captured by South Korean commandos. South Korea at the time described the two as “heinous criminals” who could not be accepted in the South as defectors.

Critics of the appeasement policy of Mr. Moon say that he skipped due process, denied them counsel, and sent them to die at the hands of the North Koreans. A central question is how those two could have killed so many others on their boat without a fight.

There’s no record of any bodies having been found, even though the South Koreans captured the boat. Mr. Suh, who became Mr. Moon’s national security adviser, “ordered an early end to an internal investigation,” according to the South Korean news agency, Yonhap.

Human rights activists protested that it was entirely against longstanding South Korean policy to return defectors, even if charged with criminal offenses. South Korean officials insisted the men’s accounts of what happened on their boat were conflicting and not convincing.

The North said they had tossed the bodies of everyone else on the boat overboard after mutinying against the captain. The two were tortured and beheaded two months after they were handed over to North Korea, according to Daily NK, a website in Seoul with cellphone contacts inside the North.

The National Intelligence Service under the current South Korean president, Yoon Suk-yeol, a conservative, wants the records of the surrender of the two fishermen to the North plus those of the case of a fisheries official who was killed by the North Koreans after his patrol boat wound up off the North’s southwestern coast.

Unlike Mr. Moon, Mr. Yoon has promised to deal strongly with North Korean threats of all kinds. The NIS charges that Park Jie-won, a veteran leftist politico who succeeded Mr. Suh as NIS director, deleted reports of the death of the fisheries official, Lee Dae-jun, in September 2020.

Mr. Park, known for his pro-North proclivities, was a highly controversial choice for NIS director under President Moon. He played a role in the first inter-Korean summit in June 2000 between a late president, Kim Dae-jung, and a late North Korean leader, Kim Jong-il, father of the current strongman, Kim Jong-un.

The South Korean Coast Guard has now debunked the Moon government’s claim that Mr. Lee was trying to defect before the North Koreans shot and killed him and then burned his patrol boat, which had strayed into North Korean waters. 

The coast guard’s initial report appears to have been fabricated to avoid offending Kim Jong-un while Mr. Moon was pleading unsuccessfully for North-South dialogue. A coast guard official said three weeks ago that it “failed to find any evidence to believe that the official had intended to defect to North Korea.”

Mr. Park, however, said the NIS charge that he had deleted “intelligence-related reports without authorization,” reported by Yonhap, was “completely groundless.”

In Seoul last week, the UN special rapporteur on human rights, Tomas Ojea Quintana, said North Korea was “responsible for violating the right and killing this fishery official.” The reason, he said, may have been to enforce the North’s “draconian laws” under “Covid-19 restrictions.” He called on North Korea “to punish those who shot him in the sea and to provide reparations to the family.”

A member of South Korea’s national assembly, Ha Tae-keung, charged that the government’s initial claim that Mr. Lee had been trying to defect was “all about defamation and lying.” At a press conference that this reporter attended, he said that officials of Mr. Moon’s  government “had hidden facts” in “a rush to judgment.”

Mr. Ha added that Mr. Moon, before stepping down as president on May 10, had sealed the records in archives, hiding the facts from investigators.

Mr. Lee’s brother, Lee Rae-jin, sitting beside Mr. Ha, said his brother “was dragged to the North Korean vessel without any reason.” Their “brutality was awful,” he said. “The international community and our government have to investigate thoroughly.”