Mandy Wrigley drove down to St. Augustine on Thursday from Columbia, S.C., not to visit her son like she used to, but to help find the person who killed him.

It's been nine months since 23-year-old Bryan Wrigley was struck by a vehicle and killed in a hit-and-run crash while riding his bike on County Road 214 in St. Johns County.

Investigators still have not made any arrests.

"This used to be a happy place for us to come," Mandy Wrigley said of the city where her son attended college.

She recently put up three billboards on Interstate 95 near Exit 311 in St. Augustine with details about the case in hopes it would lead to an arrest.

"I think the shock's worn off a little bit," Wrigley said of her son's death. "I'm still in therapy."

On April 13, her son was riding his bike when deputies said he was hit head-on. His body was found in a ditch on the side of the road.

"(The driver)'s caused us a lot of pain," Wrigley said. "And if he had just stopped, it would have been an accident."

Wrigley said she's hoping the extra signs and flyers help bring more attention to the case she and investigators are trying desperately to solve.

"They need to put themselves in my shoes," she said of whoever's responsible for the crash. "How would they feel if this young man had been found lying on the side of the road?"

The billboards show a composite sketch of the driver from witness accounts and a picture of the pickup truck detectives believe was involved in the crash -- a dark blue Ford Ranger.

Since the billboards have gone up, investigators said they have received more tips but still need help solving the case.

The Wrigleys are offering a $5,000 reward for information leading to an arrest in the case. They're also helping host fundraisers.

April 14 is the Wrigley Ride to promote cycling awareness, and part of the proceeds will go toward Bryan Wrigley's scholarship foundation, helping someone who wants to go into the medical field.

Investigators say the driver who hit Wrigley is in his late teens or early 20s. He was driving a metallic blue Ford Ranger extended cab pickup truck made between 2001 and 2003. The truck had fog lights molded into the front bumper.

If you have any information that can help solve Wrigley's case, call Crime Stoppers at 888-277-TIPS.