The suspect in the shooting of former Japanese Prime Minister Abe Shinzo is believed to have picked a highly lethal gun from the several he had manufactured.

Sources within the investigation told NHK that Yamagami Tetsuya had made multiple types of guns using steel pipes wrapped in adhesive tape.

The 41-year-old Nara resident was arrested on suspicion of attempted murder shortly after Abe was shot from behind while he was delivering a speech in Nara City on Friday.

Police say they found a homemade gun measuring about 40 centimeters long by 20 centimeters at the scene. They say they also confiscated several similar hand-made guns from the suspect's apartment.

The investigative sources quote Yamagami as saying he had made different types of guns by separately wrapping together two, three, five and six steel pipes using adhesive tape.

He also reportedly said that he had test-fired the guns after loading each pipe with a bullet, and that he had bought the parts online.

The gun used in the shooting is believed to have been made of two pipes.