The attacker, Tetsuya Yamagami, told investigators he acted because he believed rumors that Abe had ties to an organization he disliked, police said.
Japanese media reported that the man had developed hatred for a religious group his mother was obsessed with and which caused his family financial problems. The group was not specified in the reports.
On Saturday, a black hearse containing Abe’s body and accompanied by his wife, Akie, arrived at his home in the upscale residential district of Shibuya in Tokyo. Many mourners, including senior Party officials, waited for his remains and lowered their heads as the vehicle passed by.
Nara Prefecture Police Chief Tomoaki Onizuka said Abe’s murder was his “greatest regret” in a 27-year career. “I can’t deny that there were issues with our security,” Onizuka said.
“Whether it was intentional, emergency, or individuals’ ability, we have yet to find out. Overall, there was a problem and we’ll look at it from every perspective.”
The assassination of Abe ahead of Sunday’s parliamentary election shocked the nation and raised questions about whether the former prime minister’s security was adequate.
Some observers who watched videos of the attack noted a lack of attention in the open space behind Abe as he spoke.
Fumikazu Higuchi, a former Kyoto prefecture police investigator, said the images suggested security at the event was scarce and insufficient for a former prime minister.
“It is necessary to investigate why security allowed Yamagami to move freely and go after Mr. Abe,” Higuchi said on a Nippon TV talk show.
Experts also said Abe was more vulnerable standing on the ground, rather than on top of a campaign vehicle, which is usually the case, but was reportedly unavailable due to his hastily arranged visit to Nara.
“It seems that the police mainly focused on the front, paying little attention to what is behind Mr Abe, and no one stopped the suspect from approaching him,” said Mitsuru Fukuda, a crisis management professor at Nihon. university.
“Clearly there were problems.”
Fukuda said election campaigns offer voters and politicians a chance to communicate with each other because “political terrorism” was extremely rare in post-war Japan.
But Abe’s murder could lead to tighter security at crowded events like campaigns, sports matches and others.
A look at high-profile political assassinations this century
During a parliamentary debate in 2015, Abe opposed suggestions from an opposition MP to bolster his security, stressing that “Japan is a safe country.”