Chief Cabinet Secretary Yukio Edano, a lawyer-turned-lawmaker, is concurrently serving as one of the defense lawyers for a Saitama Prefecture man seeking a retrial of his conviction for a 1963 murder, the Cabinet secretariat said Sunday.

Edano's continued service in the high-profile case known as the "Sayama Incident" has drawn flak from some legal experts as violating the constitutional separation of the three branches of government.

"I should have left when I assumed a government post, but I failed to remember," Edano said in a press statement Sunday. "I would like to leave the counsel as I have assumed the post of chief Cabinet secretary."

Kazuo Ishikawa, 72, was arrested in 1963 and charged with the murder of a 16-year-old female high school student. He was given a life sentence and spent almost 32 years in jail, but later insisted on his innocence, claiming he was forced by police during interrogation to admit to the murder.

Edano joined the defense counsel in May 2006, when Ishikawa filed his third petition for a retrial with the Tokyo High Court. He is serving his sixth term in the House of Representatives since 1993.

Tomoaki Iwai, a Nihon University professor, said a conflict of interest is possible in Edano's case.

"Lawyers in defense counsels in criminal trials involving false accusations are in a position to criticize the government and investigative authorities when representing a client," Iwai said.

"Thus, (Edano's) serving as a member of the Cabinet representing the government, which could be the object of criticism, clearly clashes with his position" as a member of Ishikawa's defense counsel.