A police officer suspected of leaking a sensitive presidential document that has created a major political mayhem in South Korea was found dead in an apparent suicide Saturday, investigators said.

According to the document leaked to the media late last month, Jeong Yun-hoe, who served as an adviser for President Park Geun-hye when she was a lawmaker, is alleged to have held regular meetings with several incumbent senior presidential officials to influence state affairs including personnel matters. He has never held any official position in the current administration.

With a massive probe into the case under way, the police lieutenant surnamed Choi at Seoul Metropolitan Police Agency, together with his colleague surnamed Han, allegedly copied the document and handed it over the media and other sources.

"Choi was found dead in his car at around 2:30 p.m. today near his hometown in Icheon," a police investigator said, citing the city in Gyeonggi Province, some 80 kilometers south of Seoul. 

The 45-year-old police officer apparently used carbon monoxide gas from burning briquettes to kill himself, citing the cinders that remained in the vehicle, the investigator said, adding that Choi also had self-inflicted knife wounds in his ankle.

It is yet to be known if he left any suicide notes.

Prosecutors earlier had filed for arrest warrants for Choi and Han, charging them with leaking the presidential document. But the Seoul Central District Court dismissed the request on Friday, citing "no enough reason to put them under detention."

The controversial document was drawn by their senior colleague, Park Gwan-cheon, who had worked for the presidential office Cheong Wa Dae until early February when he was transferred to a police station in northern Seoul.

The allegations over Jeong's behind-the-scenes intervention in state affairs have emerged as a nation-rocking political scandal, putting the Park administration in the hot seat as it enters its third year in power in late February.  (Yonhap)