Police in Japan say they have arrested three former members of the Aum Shinrikyo cult, for attempting to kill the country's police chief in 1995.
Takaji Kunimatsu was shot and seriously wounded just 10 days after the sarin gas attack which killed 12 people on the Tokyo subway.
Aum Shinrikyo, a fanatical doomsday cult, was later held responsible.
Former cult leader Shoko Asahara and 11 others have been sentenced to death for their roles in the subway attack.
The three cult members arrested on Wednesday have been named as Toshiyuki Kosugi, Tetsuya Uemura and Mitsuo Sunaoshi.
Toshiyuki Kosugi was once a senior police officer himself. He initially confessed to shooting Mr Kunimatsu in 1996, but no charges were brought against him due to lack of evidence.
According to the Japanese media, Wednesday's arrests came as a result of new information gained from questioning Mr Kosugi further.
National police chief Takaji Kunimatsu nearly died after being shot on 30 March 1995, as he was leaving his Tokyo apartment.
At the time of the shooting, he was leading a nationwide investigation into the Tokyo subway attack, and police believe the shooting was apparently aimed at disrupting his inquiries.
It is still not clear exactly why Asahara ordered the Tokyo attack.
The group mixed Buddhist, Hindu and Christian tenets, and believed some kind of Armageddon was imminent.
Since the subway incident, Aum Shinrikyo has changed its name to Aleph and now insists it is harmless.
But Japan's intelligence agency says the group is still a threat to society, remaining faithful to Asahara's violent teachings.
The group's 1,600 members remain under strict surveillance.