JACKSON, Miss. — Seven months of searching for her lost son brought Bettersten Wade to a dirt road leading into the woods, past an empty horse stable and a scrapyard. The last time she’d seen her middle child, Dexter Wade, 37, was on the night of March 5, as he left home with a friend. She reported him missing, and Jackson police told her they’d been unable to find him, she said. It wasn’t until 172 excruciating days after his disappearance that Bettersten learned the truth: Dexter had been killed less than an hour after he’d left home, struck by...