(NEWSER) – It was a crime both "tragic and senseless," say prosecutors. David Peterson, 54, was out for a walk in his Seattle neighborhood last month when police say high school student Byron White tried to steal his cellphone, theSeattle Times reports. Peterson fought off the teen and called police, but informed the 911 operator that his assailant had doubled back. That's when White, 17, shot Peterson in the chest, according to police, who arrived minutes later to find Peterson dead in a pet shop parking lot, the Seattle Post-Intelligencer reports. The teen later told friends "the man had seen his face, and he had to shoot him," a detective alleges.