Tetsuya Yamagami is sent to prosecutors on July 10 on suspicion of murdering former Prime Minister Shinzo Abe. (Video by Nanami Watanabe)

The suspected murderer of former Prime Minister Shinzo Abe followed the politician on the election campaign trail the day before the fatal shooting in Nara, investigative sources said.

Tetsuya Yamagami, 41, told investigators that he had visited a hall in the city of Okayama on July 7 where Abe delivered a speech in the evening for an Upper House election candidate of the ruling Liberal Democratic Party.

Investigators confirmed that Yamagami visited the venue on July 7, but it was unclear if he actually entered the hall, they said.

Abe’s scheduled visit to Okayama was publicized a couple of days in advance through the social media accounts of lawmakers.

Nara prefectural police said they believe the unemployed suspect had checked Abe’s schedule and was looking for an opportunity to attack the former prime minister.

LDP officials said visitors to the hall in Okayama were asked to write down their names and contact information at the reception desk. Around 2,000 people entered the venue, which has about 1,700 seats.

Abe was outdoors for the speech in Nara on July 8. Video footage shows a gunman approaching Abe from behind and firing two shots.

Yamagami was immediately apprehended on the street and held at Nara-Nishi Police Station on suspicion of attempted murder. A homemade gun was confiscated at the scene.

Yamagami was driven to the Nara District Public Prosecutors Office at 9:20 a.m. on July 10 where the allegations were upgraded to murder.