The anti-corruption investigation office questioned a former defense ministry official as a power abuse suspect Thursday over allegations of external pressure placed on the military investigation into last year's death of a young Marine.

Park Gyeong-hun, the former acting chief of the ministry's National Investigation Headquarters, appeared at the Corruption Investigation Office for High-ranking Officials in Gwacheon, south of Seoul, Thursday morning, while remaining tight-lipped when asked several questions by reporters.

Park is suspected of exerting undue influence on the military prosecution's handling of the inquiry involving a young Marine who died during a mission to search for civilian victims of heavy downpours last summer.

The Marine Corps' investigation team asked the police in August last year to probe eight suspects over the soldier's death. But the military prosecution retrieved the case from the police later and reduced the number of suspects to two after alleged interference from the National Investigation Headquarters. Park was serving as acting chief of the headquarters at that time.

It appeared that Park was grilled about whether former Defense Minister Lee Jong-sup and other superiors exerted pressure ahead of the decision to scale down the number of suspects.

Over the past week, the CIO questioned Yoo Jae-eun, a legal affairs official at the defense ministry, twice as a power abuse suspect over the same allegations. The CIO probe began after the main opposition Democratic Party filed complaints against Lee and other ministry officials in September last year.

The CIO is expected to summon Lee, former Vice Defense Minister Shin Beom-chul and Marine Corps Commandant Lt. Gen. Kim Kye-hwan later. (Yonhap)