TOKYO (REUTERS, AFP) - The suspect in a fatal stabbing spree in Japan on Tuesday (July 26) was hospitalised early this year after expressing willingness to kill disabled people if the government approved, a city official said.

Police in the town of Tsukui near Tokyo contacted the suspect, Satoshi Uematsu, and he was involuntarily committed to hospital on Feb 19.

He had reportedly tried to present a letter to the speaker of the lower house of Japan's Parliament threatening to attack two care centres - including the one in Tsukui - and kill 470 residents, Japanese media said. Uematsu had said it would launch a "revolution" that would "stimulate the economy and prevent World War III".

In the letter he also presented his vision of a society in which the seriously handicapped could be euthanised with the approval of family members as "handicapped people only create unhappiness".

AFP reported that Uematsu had been hospitalised on the same day he left his job, but was discharged 12 days later when a doctor deemed he was not a threat. While hospitalised, Uematsu was diagnosed as suffering from paranoia as well as being dependent on cannabis

People in Uematsu's neighbourhood, about a 10-minute walk from the crime scene, expressed disbelief at the killing, AFP reported.

He was a "normal, nice boy" who always smiled and offered a greeting, said next-door neighbour Akihiro Hasegawa. "This is unbelievable," the 73-year old told AFP, adding that Uematsu lived in the house with his parents until they moved out four or five years ago.

Hasegawa also said that he had seen an extensive shoulder-to-chest tatoo on Uematsu and there was a rumour in the neighbourhood he might have been fired from the facility because of it.

Uematsu had also reportedly told police he had been fired from the facility and held a grudge against it, broadcaster NTV said.