Rep. Hong Ik-pyo, floor leader of the main opposition Democratic Party of Korea, speaks during a party meeting at the National Assembly, April 23. Yonhap

The floor leader of the main opposition Democratic Party of Korea (DPK) said Tuesday that the first step President Yoon Suk Yeol should take for change is to accept a special prosecutor investigation into allegations surrounding the death of a young Marine.

Following the resounding defeat of Yoon's ruling People Power Party in the April 10 parliamentary elections, Yoon has pledged to initiate change, including improving communication with the people and the opposition bloc.

One of the first issues the DPK is pushing for after the election victory is to mandate a special counsel investigation into allegations of unfair interference with a military probe into what contributed to the death of Cpl. Chae Su-geun. Chae was killed last July during a search mission for downpour victims.

"If the president and the ruling party do not cooperate with the parliamentary passage of a special prosecutor investigation regarding Cpl. Chae, it would run directly counter to the public opinion expressed in the general elections," Rep. Hong Ik-pyo said during a party meeting at the National Assembly.

Former Defense Minister Lee Jong-sup is under investigation for allegations of exerting external pressure on the military investigation into Chae's death. Lee was appointed ambassador to Australia last month but resigned in less than a month amid the allegations.

The DPK has also raised suspicions that the presidential office was involved in the interference, and Hong said that the investigation should delve into alleged interference by Lee Shi-won, a presidential secretary, in the case. (Yonhap)