Sheriff Rowles, 73, thinks about the crime that for a while, at least to the outside world, defined Jasper. He sees things this way: What happened on an old country road is a permanent scar that time is finally healing. “Do we ever get over something like that? No,” he said. “And we shouldn’t. But it finally doesn’t come up in conversations every day any more.”

On that Saturday night, the three white men were riding around Jasper. Mr. Byrd, who was black, was walking home after drinking with friends when the driver of the truck, Shawn Allen Berry, offered him a ride. At some point overnight, the three attacked him, spray painted his face, then used a logging chain to tie him to the rear bumper of the truck. They drove along Huff Creek Road, an isolated path lined thick with pine and sweet gum trees, for three miles as Mr. Byrd was helplessly flung side to side. His naked body — decapitated, dismembered, discarded — was found in front of a black cemetery just outside Jasper.

By the Sunday afternoon, Sheriff Rowles and Sergeant Carter were at the Byrd family’s doorstep. Ms. Boatner still remembers the tiniest details of those moments. She still recalls the stricken way Sergeant Carter, a childhood friend who is now a captain, looked at her and the stillness of the room before her mother’s cries. Ms. Harris still remembers the panicked phone call from a sister and the way her words ran together, “gethomenow.” Sheriff Rowles remembers the heartbreak in Stella Byrd’s eyes.

“He was tortured like an animal,” Ms. Harris said, her words sharpened by anger. “I can’t see a human being doing this to another if you have any amount of humanity in you.”

Initially, Sheriff Rowles believed Mr. Byrd was the victim of a hit-and-run accident. But the depraved method of death, the gruesome trail left behind and a police colleague’s insistence the crime was racially motivated, convinced him that this was something different, something dark.