Pressure on the main opposition Democratic Party of Korea and the previous administration is growing, with the prosecution honing in on Democratic Party leader Lee Jae-myung and past developments that could implicate former President Moon Jae-in.

The opposition party, for its part, is denouncing the investigations as "political oppression," increasing the possibility of deepening the rift between the ruling and opposition blocs.

Death and repatriation

The prosecution is investigating two incidents -- the killing of a South Korean fisheries official by North Korean soldiers in 2020 and the repatriation of two North Korean sailors in 2019 -- that implicate officials of the former administration, and by extension former President Moon.

Two high-level officials from the Moon administration – former Defense Minister Seo Wook and former Coast Guard Commissioner General Kim Hong-hee – were arrested on Saturday over their alleged mismanagement of the fisheries official’s death.

Fisheries official Lee Dae-jun was killed by North Korean soldiers on Sept. 22, 2020, after going missing in South Korean waters. The South Korean Coast Guard at the time concluded that Lee had attempted to defect to North Korea, but the Yoon administration overturned the conclusion.

The prosecution suspects that the Moon administration deliberately closed the case without evidence of Lee’s intent to defect in order to maintain friendly relations with Pyongyang. The prosecution raided the National Intelligence headquarters on July 13, and on Aug. 16 raided more than 10 locations. The August raids included the houses of Park Jie-won, Suh Hoon and Seo Wook, who served as NIS chief, defense minister and head of the presidential National Security Council, respectively, at the time of civil servant's death.

After the raids, former NIS Chief Park Jie-won denounced the investigation as incomprehensible, as it was clearly based on “political standards.”

The Board of Audit and Inspection asked Park and Suh Hoon to appear for questioning, and Moon to answer questions in writing, but none of them accepted the request.

At the same time, the repatriation of two North Korean fishermen in 2019 resurfaced since last June, bringing forward allegations that the former government neglected human rights. The controversy was ignited on July 11 as the spokesperson for the Unification Ministry Cho Joong-hoon reversed his initial position.

“The decision to repatriate them was wrong. The North Korean fishermen should have been considered as South Korean citizens,” Cho said.

At the time of their repatriation, the government claimed that the two North Koreans had fled to the South after murdering 16 people, and that they did not show any sincere intention to defect. There was no choice but to repatriate them, as it was difficult to punish them in South Korea, the government concluded.

The prosecution accelerated the investigation, summoning and questioning Moon's Chief of Staff Noh Young-min on Wednesday. Prosecutors suspect that Noh was involved in the case, as he presided over a meeting on Nov. 4 which confirmed the two North Koreans’ repatriation.

Neverending Daejang-dong

Meanwhile, the investigation surrounding Lee Jae-myung has grown to include alleged illegal sources of political funding.

The Daejang-dong development scandal has been Lee’s Achilles heel since the presidential campaign. Lee claims that he had done his best to retrieve profits from private corporations and benefit citizens for the development of Daejang-dong and its surrounding area in Seongnam, Gyeonggi Province while serving as the mayor of the city. The ruling People Power Party and prosecution accuse him of getting inappropriate profit from the project.

The case has recently spread into illegal political funding allegations, as Yoo Dong-kyu, a businessman related to the development project, stated that he had handed over 800 million won ($559,000) to Kim Yong, one of Lee’s closest confidants.

Kim was arrested on Wednesday. The prosecution raided his office located at the Democratic Party’s headquarters on the same day, but withdrew after an eight-hour standoff with lawmakers.

The Democratic Party and Lee are countering the allegations by demanding that a special probe team investigate the case comprehensively, including all suspicions related to President Yoon Suk-yeol as well.

At a special press conference held at the National Assembly on Friday, Lee urged President Yoon and the ruling party to agree to launching a special probe team to conduct a comprehensive investigation related to the Daejang-dong development project, which includes President Yoon’s deliberate mishandling of a Busan Savings Bank's case when he was a prosecutor general.

"If the president and the ruling party are confident (of having done no wrong), there will be no reason to reject the special prosecution," Lee added.

Lee cited how at a televised presidential debate on March 2, he had asked Yoon whether Yoon agreed with launching an independent probe team, to which Yoon avoided giving a direct answer. This suggests that the president is also implicated in various suspicions surrounding the case, Lee claimed.

However, it is unclear whether the independent counsel will be launched, as the People Power Party has already flatly rejected the idea.

"If the ruling party refuses (an independent probe), we will make sure to push it through with the power of the Democratic Party," Lee said, referring to the opposition party’s majority in the National Assembly. However, the independent probe’s prospect is dim, as the People Power Party’s Rep. Kim Do-eup heads the legislative committee -- the final gateway for a bill establishing such a probe. In addition, President Yoon can veto the bill even if it passes.

The Democratic Party said it is planning to devote its energy into drafting an independent probe team bill and elicit public support.