The Nara District Court has approved the detention of a man accused of fatally shooting former Prime Minister Shinzo Abe until Nov. 29 to examine his mental fitness, a source familiar with the case said Saturday.

The pre-indictment move by the prosecution toward 41-year-old Tetsuya Yamagami comes amid expectations that questions over the shooter's criminal liability will form a major part of a forthcoming trial.

Even as prosecutors keep the suspect held for psychiatric evaluation to see if he was mentally competent at the time of the attack and to increase its chances of a successful prosecution, his defense could still request one after indictment, extending the pre-trial process.

Yamagami is being investigated for murder after Abe was shot at close range while giving a campaign speech on a traffic island in the western city of Nara on July 8. He was arrested on the spot.

The Penal Code states that individuals with diminished capacity are subject to reduced punishment, while anyone whose actions are attributed to insanity cannot be punished.

Yamagami has told investigators that he held a grudge against the Unification Church, a religious group known for its mass weddings, and targeted Abe because he thought the former prime minister had links to it, according to investigative sources.

His uncle has told reporters that his mother donated large sums of money to the church -- formally known as the Family Federation for World Peace and Unification -- and subsequently went bankrupt in 2002, ruining the family.

The defense for Yamagami is expected to build its arguments around whether he can be held liable for his actions or to what extent he was mentally competent, as there is a leap of imagination from having animosity toward the church to targeting Abe.

Lay judges could examine the case, and it would be advantageous for prosecutors at trial to present the expert view of a doctor they picked, assuming the doctor would find that Yamagami can be held criminally responsible.

But objectively ascertaining a defendant's mental state when a crime is committed is difficult and can be affected by factors such as the examiner's expertise.

A defense-requested examination could also produce a result that contradicts that of the prosecution.

In a separate development, investigative sources said Saturday that investigators plan to examine the lethality of homemade guns confiscated from Yamagami's residence.

If the deadliness of the weapons, including the one used in the shooting, is confirmed, authorities will consider building an additional case based on the firearms control law and the ordnance manufacturing law, the sources said.

Including unfinished guns, seven firearms were confiscated from Yamagami's home by police, among them a gun with three barrels. The shotgun-like weapon found at the scene of the shooting consisted of two metal pipes bound by tape and could fire six projectiles from each pipe at once.

Yamagami has told investigators that he initially considered making a bomb but decided not to because it would affect unconnected people. Instead, he made guns that he "could easily fix on a target," according to the sources.

In the case of the 2019 Kyoto Animation arson that killed 36 people, Shinji Aoba spent around half a year under prosecutors' detention for expert examinations. He was indicted only after that, in 2020. But a re-examination requested by the defense afterward and other factors have left the start of his trial undetermined.