A former chief of the Marine Corps' investigation unit has refused to undergo questioning by military prosecutors after he was booked on charges of "insubordination" related to an internal probe he led into last month's death of a Marine during monsoon rescue operations.

Issuing a statement Friday as he was supposed to appear for questioning, Col. Park Jung-hun defended his decision to hand over probe findings to the police and argued that defense ministry prosecutors illegally retrieved the documents that he lawfully transferred.

Park said he rejects an investigation by the military prosecution as a fair inquiry cannot be conducted by a defense ministry organization that has exerted external pressure and issued unjust orders.

The colonel said he did his best in the internal probe and gave a report of his findings to the Marine Corps commandant, the Navy Chief of Staff and the defense minister but that he was subjected to undue pressure several times from the defense ministry.

He said he would do the same if he had to do it all over again, stressing that he knows nothing about politics but remained faithful to the Marine Corps spirit, and also mentioned President Yoon Suk Yeol's order to thoroughly investigate the marine's death to prevent a recurrence.

Park was dismissed from his post after handing over probe findings to the police despite the defense minister's order to hold off on the transfer, with the ministry viewing the act as insubordination.

The ministry has also condemned Park's refusal to face an inquiry as "highly inappropriate," saying such action dilutes the essence of the case, impedes a fair probe and adversely affects morale, expressing strong regret.

Last month, Lance Corporal Chae Su-geun died in Yecheon County during a search mission to find victims of heavy downpours.