Police officers on duty at the venue where former Japanese prime minister Shinzo Abe was shot didn't recognise a suspicious man in the crowd until hearing the first gunshot, Japan's public broadcaster NHK reported on Saturday.
Abe died after being shot Friday by a gunman during a speech in the western city of Nara while campaigning for Sunday's upper house election.
Police arrested gunman Tetsuya Yamagami, 41, a resident of Nara, at the scene.
Yamagami worked for the Maritime Self-Defence Force (MSDF) for three years until around 2005, NHK quoted defence sources as saying.
He was arrested at the site and local police retrieved what appeared to be a handmade gun from the vicinity of where the former prime minister was shot, according to government reports.
Japan's National Police Agency said that considering the circumstances of the crime scene, it plans to review the day's security arrangements for the former prime minister, NHK reported.
The agency cites possible problems with police arrangements for patrolling the area behind where Abe was speaking, the report said.
The report further states that some security experts point out the seriousness of police officers failing to stop the gunman from firing at Abe.
"They say, first and foremost, the officers should have prevented the assailant from getting anywhere near Abe."
On Saturday, the head of police in Nara Prefecture, Kazuo Ohashi, said the potential security issues in the case of the assassination of Shinzo Abe cannot be denied.
'There is no denying that there was a security issue there,' the official said in a press conference.
According to Ohashi, the assassination was an act of 'inexcusable barbarism', and it is necessary to investigate the case 'in the most thorough way'.
Japanese prime minister Fumio Kishida earlier in his live address to the country on Friday said 'this is not a forgivable act', and that authorities would 'take appropriate measures to handle the situation'.
Kishida further said that the motive behind Abe's shooting is not known.
The Japanese PM also requested everyone to not speculate about any political ramifications at the time.
