The investigation into the assassination of Japan’s former Prime Minister Shinzo Abe revealed on Sunday that the man behind the killing checked YouTube when making the firearm used in the attack, local media reported citing sources.According to the Japan Times, the investigative sources said that Tetsuya Yamagami, the gunman has stated that he tested a homemade gun at a facility connected to a religious group he harboured a grudge against. Yamagami said his mother made a “huge donation” to the organization, which he believes Abe was associated with.Following Abe’s assassination, the police found items that are believed to be explosives and multiple homemade guns at Yamagami’s home, similar to the one used to kill Abe. Nara prefectural police said it appears that the suspect checked YouTube ahead of the attack in repeated attempts to make firearms, the Japan Times reported.The gun Yamagami made to shoot Abe was “designed to fire six projectiles at a time,” sources said. The weapon was composed of two metal pipes held together with tape and employing projectiles placed in small plastic shells fired from both barrels. It was similar to a shotgun, they said.The sources also said that multiple wooden boards, measuring around 1 square meter each, with holes apparently made during weapon testing were found in Yamagami’s car.The suspect has said an aluminium-covered tray found in the vehicle was used to dry gunpowder, according to the sources. Yamagami was also quoted as saying he had attempted to make a bomb and he appears to have gone through a process of trial and error to produce such a device, the Japan Times reported.Tetsuya Yamagami, a 41-year-old resident of Nara City, in western Japan shot Abe while he was delivering a campaign speech on Friday.The man denied that he committed the crime because he was opposed to Abe’s political beliefs, according to the police.The police said that Abe died from blood loss. The police also said that the autopsy determined that there were two gunshot wounds, on his upper left arm and neck.Abe, Japan’s longest-serving prime minister, stepped down in 2020 citing health reasons.He was prime minister of Japan twice, from 2006-07 and again from 2012-20. He was succeeded by Yoshihide Suga and later by Fumio Kishida.