Japanese prosecutors will indict a 42-year-old man on murder and other charges over an arson attack in July last year on a Kyoto Animation Co. studio that killed 36 people and injured 33 others, investigative sources said Thursday.

Shinji Aoba, who was arrested in May, has likely been determined by medical experts to be mentally competent and can be held criminally liable for the attack, one of Japan's worst mass murder cases.

Aoba has been confined for expert examination since June. His arrest came after authorities judged he recovered sufficiently from life-threatening burns sustained from the incident on July 18, 2019.

The company, often referred to as "KyoAni" at home and abroad, is known internationally for producing many popular animation works such as "K-On!" and "The Melancholy of Haruhi Suzumiya."

Following his arrest, Aoba admitted to setting fire to the studio, saying, "I thought I could kill many people by using gasoline," according to police.