Following the murder of 19 people at a care facility by a former staff member, experts are trying to determine the motivation behind the attack.
In the leading hypothesis so far, the killer had anger management problems coupled with ill feelings toward people with disabilities.
Satoshi Uematsu, 26, was arrested on Tuesday following the attack that also left another 25 people injured at the facility in Sagamihara, Kanagawa Prefecture, where he once worked.