When North Korean soldiers found a South Korean fisheries official in their territorial waters, they shot him and burned the body – an incident so shocking it later prompted Kim Jong Un to apologize.

Details are sketchy — and mostly classified — but exactly how and why the officer floated in a life jacket in September 2020 over the sea line known as the Northern Limit Line has become a bitter political debate in the South.

Was 47-year-old civil servant Lee Dae-jun a potential defector fleeing gambling debts, as then-President Moon Jae-in’s government said, citing intelligence agencies that then sealed them off for 30 years?

Or is this version of events in fact a high-level smear campaign and cover-up, as Yoon Suk-yeol’s new government has claimed when it raided the home of a former spymaster and launched legal action over the previous government’s handling of the case?

The intelligence agencies claim their former boss, Park Jie-won, destroyed evidence proving Lee had no plans to move to Pyongyang.

Park told AFP the charges were “political revenge on the previous administration” and dismissed the allegations as unfounded.

Seoul’s new government has also reopened investigations into a second explosive case in which two North Korean fishermen who confessed to killing 16 crew members at sea were deported in 2019.

A dramatic video showing the pair seemingly reluctantly being dragged through the heavily fortified Demilitarized Zone (DMZ) and brought back north has been released by Yoon’s conservative government.

Moon’s government at the time said the brutal nature of the killings meant the men were not entitled to the usual protections of North Korean defectors and could not be considered fugitives.

The political row over the two cases highlights the risks of a highly biased interpretation of secret intelligence agencies and the law, analysts say.

Critics argue that the hawkish Yoon, who is struggling with record-low approval ratings just months after taking office, is resorting to old-fashioned sayings to salvage his popularity with disgruntled voters.

“For conservatives, these two cases are an example of how liberals take a submissive attitude towards the North,” lawyer and columnist Yoo Jung-hoon told AFP.

But “the timing of the investigation, which came right after the change of power, raises questions about a political motive behind it,” he added.

Supporters of Yoon, a former prosecutor who won a close election in March and vowed to crack down on Pyongyang after years of failed diplomacy, say he is simply trying to solve the cases.

“It would be a bigger problem if prosecutors ignored the allegations and buried the cases, fearing it was a ‘political investigation,'” Shin Yul, a professor at Myongji University, told AFP.

Legal experts say the cases have revealed contradictions in the country’s constitution.

Trial of the fishermen in South Korean courts would have been unprecedented, as it was unclear whether local courts had jurisdiction.

A clause in South Korea’s constitution describes the country’s territory as “the Korean peninsula”.

Yoon has suggested that this clause meant the men should have been considered South Korean citizens and tried at home.

But the next clause promises to work towards a “peaceful reunion” with the North, acknowledging the reality that there are two distinct countries on the peninsula.

“Seoul needs to take a realistic approach to dealing with the North,” said Kim Jong-dae of the Yonsei Institute for North Korean Studies.

Yoon’s government has accused Moon’s government of sending the fishermen “straight to death row” by repatriating them north.

But critics say the president has prioritized “revenge policies” over addressing more pressing policy issues like spiraling inflation and a falling currency.

Attempting to prosecute officials without providing counter-evidence in either case looks suspicious, Kim Jong-dae said.

“The government is aiming for punitive governance with prosecutors at the helm,” he said.

“It’s one thing to ask questions and demand answers about how the previous government handled the two cases. But investigating ex-officials is another matter altogether, which inevitably raises suspicions of political motives.”