Yamagami was pictured at the scene holding a large boxy black object that appeared to have two barrels.
Officers in protective gear began searching the suspect’s home after 5pm and confiscated “several handmade gun-like items”.
The suspect, who addressed police in a “matter-of-fact way”, told officers he had worked for the Maritime Self-Defense Force – Japan’s navy – for three years from 2002, but these details are also under investigation.
Yamagami also told police he had learned about Abe’s visit online, the officers said.
They added that they were probing whether there were any problems with security at the campaign event where the assassination took place on Friday morning.
“We will take appropriate measures if problems were discovered.”