The head of police at Nara, where Abe was shot, says there were problems with safety measures in guarding the former premier.
Japan’s best-known politician was on the campaign trail in the western region of Nara when a gunman opened fire at close range.
“I believe it is undeniable that there were problems with the guarding and safety measures for former prime minister Abe,” Tomoaki Onizuka, head of the Nara prefectural police, told reporters on Saturday.
“The urgent matter is for us to conduct a thorough investigation to clarify what happened,” he said.
He did not offer any immediate details on specific shortcomings of the security plan, but said he felt a heavy sense of responsibility.
“As the regional police chief responsible for safety and security of the region, I took necessary steps and built structures for security and guarding,” he said.
Police facing questions
The Japanese police now face many questions about how the shooting could have happened, with experts asking why those working in Abe’s security detail were unable to prevent the attack.
“I don’t think there are enough firearms precautions in Japan given its strict gun laws,” one security expert was quoted as saying by the Nikkei newspaper.
The National Police Agency now intends to review its security arrangements for the protection of prominent figures, according to media reports.
Japan is considered one of the safest countries in the world and has extremely strict gun laws.
The assassination happened in the run-up to elections for the upper house of parliament on Sunday. The vote is to take place as planned despite the attack, according to the government. The coalition headed by Abe’s Liberal Democrats is expected to hold on to its majority.
Abe, 67, was shot from behind, minutes after he started his speech in Nara. He was airlifted to a hospital for emergency treatment but was not breathing and his heart had stopped.
He was later pronounced dead despite emergency treatment that included massive blood transfusions, hospital officials said.
Police at the scene arrested Tetsuya Yamagami, a former member of Japan’s navy, on suspicion of murder.
Police said he used a gun that was obviously homemade – about 40cm (15 inches) long – and they confiscated similar weapons and his personal computer when they raided his nearby one-room apartment.
Police said Yamagami was responding calmly to questions and admitted to attacking Abe, telling investigators he had plotted to kill him because he believed rumours about the former leader’s connection to a certain organisation, which police did not identify.
According to media reports, Abe’s body is to lie in state on Monday, ahead of a private funeral ceremony for his family on Tuesday.