The suspect accused of fatally shooting former Prime Minister Abe Shinzo had reportedly posted a letter before the attack, implying that it was planned in advance.

The letter detailed grudges against a certain religious organization. It also described Abe as just one of the most influential sympathizers, not the primary adversary.

A resident of Shimane Prefecture says he noticed the letter had been delivered to him on July 13.

He runs a blog critical of the Family Federation of World Peace and Unification, formerly known as the Unification Church.

The postmark has no clear date but the letter is believed to have been mailed in Okayama City.

Investigative sources say that on July 7, the day before the shooting, the suspect visited an election campaign venue in Okayama City, allegedly with the intention of attacking Abe.

Investigators believe the suspect, Yamagami Tetsuya, carried out the attack because of his mother's large financial donations to the religious group.

The man who received the letter says it explained the author's circumstances and relationship with the group, as well as the grudges he felt toward it.

Regarding Abe, the letter says the author is aware he is not the real enemy and that he is merely one of the most influential sympathizers with the group.

But the author says he has no room in his mind at the moment to consider what consequences Abe's death could bring to politics.

Along with the letter, the envelope also contained copies of documents his mother exchanged with the religious group over the reimbursement of money she had donated.

The suspect's address in Nara City was written on the envelope.

Police say they are trying to confirm whether the letter was sent by the suspect, and are investigating the circumstances surrounding it.