TOKYO, July 19 (Reuters) - The man suspected of torching an animation studio and killing 33 people in Japan's worst mass killing in two decades had been convicted for robbery and treated for mental illness, public broadcaster NHK said.
The suspect, whom police named as Shinji Aoba, 41, was sentenced to 3-1/2 years for robbing a convenience store in 2012, NHK said. Police officials in Chiba Prefecture, east of Tokyo, declined to comment when reached after hours.
After his release, Aoba spent some time in facilities for former convicts. He had also received treatment for mental illness from caretakers who visited his home, NHK said. (Reporting by Kiyoshi Takenaka Writing by William Mallard; Editing by Nick Macfie)