Police served a fresh arrest warrant Saturday on the suspect in an attack on Prime Minister Fumio Kishida last month alleging he illegally manufactured explosives.
Ryuji Kimura, 24, from Hyogo Prefecture was arrested on April 15 at the scene on suspicion of obstruction of business for allegedly throwing an explosive device at Kishida just before the prime minister was about to make a stump speech in Wakayama, western Japan. Kishida was not injured.
Investigators said they have determined that a substance confiscated from Kimura's home was gunpowder. The dark gunpowder was found along with metal nuts in one of the two pipe bombs collected at the scene, they said.
While Kimura has remained silent since his arrest, court documents show he may have harbored a grudge after he was unable to file for candidacy for a House of Councillors election held last year.
Kimura filed a lawsuit with the Kobe District Court in June last year seeking 100,000 yen ($742) in damages for mental distress, while asserting the requirements to be at least 30 years old and pay a 3 million yen deposit to run in the election violated the Constitution, which guarantees equality under the law.
Kimura also submitted a document criticizing Kishida's Cabinet for holding a state funeral for the late Prime Minister Shinzo Abe, saying the event was "forced through with only Cabinet approval" and without parliamentary deliberations, adding "such a challenge to democracy cannot be tolerated."