BRUNSWICK, Ga. (AP) — He was at a crossroads, his life stretching out before him, his troubles largely behind him. He had enrolled at South Georgia Technical College, preparing to become an electrician, just like his uncles. But first, he decided, he would take a break. College could wait until the fall.

To help keep his head clear, he ran, just about every day. Off he'd go, out of the doors of his mother's house, down the long street toward Fancy Bluff Road. Then would come the right turn onto the two-lane road lined by oak trees draped with Spanish moss.

About a mile and a half into his usua...