(1:38)NEW YORK -- A man who killed four people at a Manhattan office building bought the rifle he used in the attack and the car he drove across the country from his supervisor at a Las Vegas casino, authorities said Wednesday. At Tamura's Las Vegas studio apartment, investigators found a note with a different troubled message, police said Wednesday. The supervisor legally bought the AR-15-style rifle he sold to Tamura for $1,400, police said, adding that they had erred in saying earlier that the supervisor supplied only parts of the rifle. Police didn't identify the supervisor, who has been forthcoming with them and hasn't been charged with any crimes. In September 2023, he was arrested on a misdemeanor trespassing charge after allegedly being told to leave a suburban Las Vegas casino and becoming agitated at being asked for his ID.