Police in Nara prefecture in western Japan said they would review security measures for former prime minister Abe Shinzo after he was shot dead on Friday.
The 41-year-old suspect, Yamagami Tetsuya, lives in the city of Nara and was arrested at the scene after shooting Abe who was speaking to a crowd as part of the election campaign.
At a press conference on Friday evening, Nara prefectural police said they had set up a 90-member task force and were investigating the case as a murder.
Officials said they learned of Abe’s visit to Nara the night before, but there was still enough time to prepare the necessary security arrangements.
Police said the suspect admitted shooting Abe and explained he had a grudge against a certain organization, which he believed the former prime minister was involved with.
Yamagami told police that his mother was deeply involved in the organization and donated a lot of money, which caused serious problems for his family.
Police quoted the man as saying he learned of Abe’s visit to Nara City from the internet and traveled to the site by train.
Officials said the homemade gun used to kill Abe was about 40 centimeters long.
Police said they searched the suspect’s residence and seized several metal and wooden homemade firearms, which also resembled the one used in the attack.
They also confiscated the suspect’s personal belongings, including a shoulder bag, smartphone and wallet. They believe the attacker was carrying the weapon used in the murder in a navy blue cloth bag measuring 40 centimeters long.
Police quoted Yamagami as saying he served in the Self-Defense Forces for three years until 2005, and is currently unemployed.