Abe was killed with a homemade gun while he was making a campaign speech in July.
The incident underscores a growing wave of protests against the funeral for Shinzo Abe, who was one of the most divisive leaders in postwar Japanese politics.
Former Japanese Prime Minister Shinzo Abe was shot to death in July.
National Police Agency Chief Itaru Nakamura's announcement came as his agency released a report on how it failed to protect Abe's life on July 8.
Prosecutors have until Nov. 29 to decide whether Tetsuya Yamagami will be formally charged with murder.
Video shows the moment former Japanese Prime Minister Shinzo Abe was shot at a campaign rally.
Abe "was a champion of the Alliance between our nations and the friendship between our people," Biden said.
Abe was later pronounced dead despite emergency treatment that included massive blood transfusions, hospital officials said.
Abe, 67, was shot from behind in western Japan while giving a campaign speech. He later died at the hospital.
Abe was pronounced dead in hospital despite emergency treatment that included massive blood transfusions, officials said.