Prosecutors have begun interrogating a 31-year-old former police officer who confessed last spring to the March 1995 shooting of National Police Agency chief Takaji Kunimatsu, according to investigation sources.

Toshiyuki Kosugi, 31, who was dismissed last November by the Metropolitan Police Department, was formerly a member of Aum Shinrikyo. Kosugi has been indicted for allegedly leaking information regarding the 1995 police raid on the cult to Aum leaders, but police have so far taken no official action against the former officer over the Kunimatsu shooting, despite his own confession to investigators.

Police sources have said Kosugi's testimony still cannot be considered reliable because investigators have so far been unable to find material evidence to back it up. Despite two months of police searches, they failed to find the handgun used in the shooting, which Kosugi said he dumped in the Kanda River near JR Suidobashi Station.

Kosugi has mentioned the names of some senior Aum leaders, including Yoshihiro Inoue and Kiyohide Hayakawa, whom he said were with him when he shot Kunimatsu in front of the NPA chief's condominium in Tokyo's Arakawa Ward. But all of the Aum leaders, most of whom have admitted guilt in their trials on other alleged cult crimes, have flatly denied being involved in the shooting of the NPA chief.