POLICE FOUND 19 spent shell casings scattered in the San Diego street where Gregory Benton was murdered on April 12, 2014. Benton and his cousin had gone to buy cigarettes, a witness later said. As they returned to a family party, two men pulled up in a car behind them. They got out, and at least one of them opened fire.
Witnesses didn’t get a good look at the men or the car, so when police sat down to review their leads, the shell casings were the best evidence they had. They sent the casings to the San Diego Police Crime Lab, which just happened to be trying out a new DNA testing technique.