(SAGAMIHARA, Japan) — Hatred appears to be what fueled a young Japanese man who went on a stabbing rampage, killing 19 people Tuesday at a facility for the mentally disabled where he had been fired. Months earlier, he reportedly gave a letter to Parliament outlining the bloody plan. When he was done, Satoshi Uematsu, 26, had left dead or injured nearly a third of the almost 150 patients at the facility in a matter of 40 minutes in the early Tuesday attack, the deadliest mass killing in Japan in decades.