Police say Yamagami, 41, is suspected of murder, but has not been formally charged. Yamagami said he held a grudge against a particular group he believed Abe had ties to and with which his mother had been involved, according to Japan’s public broadcaster NHK and Kyodo news agency, citing police. Nara police said on Monday that Yamagami may have carried out a test fire in the early hours of Thursday against the building of “a certain group” in Nara prefecture, using the improvised weapon he later killed Abe with. Investigators said a vehicle believed to be Yamagami’s car was seen on security cameras near where Thursday’s test shot allegedly took place. Police declined to name the group and security plans have not been released. CNN could not independently confirm which group the suspect was referring to. The suspect’s mother was a member of the Family Federation for World Peace and Unification, popularly known as the Unification Church, Tomihiro Tanaka, president of the church’s Japan office, said in a statement on Monday. The suspect was never a member of the church, while his mother was a member who attended church events about once a month, the statement said. Tanaka added that the organization would cooperate with investigators if asked. Homemade gun: Yamagami told police he watched YouTube videos to help him make his guns, NHK reported Monday, citing investigators. He practiced shooting the weapons in the mountains days before the killing, and police found wooden boards with bullet holes in the suspect’s vehicle, according to NHK. Photos from the scene Friday show what appeared to be a gun with two cylindrical metal barrels wrapped in black tape. Yamagami also told investigators that he originally intended to kill Abe using explosives at an event in Okayama Prefecture, a three-hour drive from Nara, NHK reported – but reportedly changed his plan because of possible difficulties attending the event. As a national leader, Abe became associated with multiple groups, organizations and causes, as is customary in any democracy. It is unclear whether Abe was connected to any group the suspect was talking about. When asked if the suspect was working alone or with anyone else, police said they were investigating all possibilities.