Prosecutors have told relatives of victims killed in the 2019 arson attack of Japanese anime studio Kyoto Animation Co. that they want the suspect's trial to begin between September and December, an investigative source said Thursday.

A specific date has not been set for the trial of Shinji Aoba, 44, who was indicted in December 2020 for murder and arson after setting fire to the studio's premises, leading to the deaths of 36 artists and others on July 18, 2019.

Photo taken July 18, 2019, from a Kyodo News helicopter shows smoke billowing from the three-story studio of Kyoto Animation Co. in Kyoto. (Kyodo) ==Kyodo

Pretrial proceedings and jury appointments are expected to proceed before the public trial, the date of which is still being arranged by the prosecutors, defense lawyers and the Kyoto District Court.

Prosecutors are currently checking with the bereaved whether they want to participate in the trial. With many expressing interest, the court is considering expanding the space necessary for them, according to the source.

The biggest contention at the trial would be whether the defendant is mentally competent to be held criminally responsible for the attack.

Aoba was given a mental evaluation before the Kyoto District Public Prosecutors Office indicted him on Dec. 16, 2020 on five counts of crime including murder and arson.

A second evaluation was conducted at the defense's request and that was completed in March 2022.

Aoba suffered severe burns himself as a result of the attack and underwent advanced treatment before he was arrested in May 2020.

The attack on the company known for a long line of popular anime works, including "K-On!" and "The Melancholy of Haruhi Suzumiya," shocked many domestic and international fans who affectionately call it "KyoAni."

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