There have been six unsolved fatal hit-and-run crashes in St. Johns County since April 2011.
Most recently, Stephon Sweet (pictured below), 53, was killed in Hastings Saturday night in a hit-and-run, and Juan Jesus Zalazar, 34, a St. Augustine motorcyclist, was killed Friday in one.
Deputies say none of the unsolved cases are cold, and clues are still coming in, but they're asking for the public's help to help make arrests.
Deputy Joseph McGinnis is a crash reconstruction expert with the St. Johns County Sheriff's Office. He's also the lead detective on three of the fatal hit-and-runs being investigated.
"All three are yet to be solved, but we are still working evidence in each of the cases," McGinnis said. "Hit-and-run crashes are a unique challenge just because of the lack of witnesses at the scene. But when these crashes do occur, you have a lot of physical evidence in most cases that give us an opportunity to follow up."
The St. Augustine Police Department and Florida Highway Patrol are investigating the other three hit-and-runs.
McGinnis said it's not easy because most of them happen at night, and the only witnesses are the driver and the victim who doesn't live to tell about what happened.
That's why McGinnis pairs autopsies with evidence at the scene, then looks for cars or trucks that could have that kind of damage.
"If the car were to hit me this kind of an orientation, I'm going to come up and and up on top of the hood," he demonstrated. "You will see dents on top of the hood. And I could possibly go up to the windshield. If it's more of a glancing blow on this and here, you're not going to see me go up as much over the hood at all, but you're going to see me more along the line and impact. This is what we call in an A-pillar right here or the plastic mirrors will come right off as well."
McGinnis said he and the other detectives will never give up seeking justice for those who were left behind at the scene, like Bryan Wrigley and Haley Smith.
"In many cases you have a driver who may not even realize that they struck a person," McGinnis said. "So it's just a matter of just trying to talk with people in the area to see if they recognize a vehicle that came through the area at that time."
McGinnis said residents can keep an eye out for people who have body damage to their cars without any reason or maybe made some quick repairs. He said neighbors should also look for changes in behavior, and those who even think they have useful information should call Crime Stoppers at 888-277-TIPS.