The family of a Rutherford County man shot to death alongside Interstate 24 hopes a new billboard will stir up clues about his death.Jackie Warpoole, Jr. was gunned down in his car on the morning of December 15.A passerby found the 47-year-old behind the wheel of his silver Dodge Magnum near the Almaville Road exit not far from his Smyrna home. A month has passed and still police have very little information to go on.The family hopes reward money and a billboard with the victim's picture will generate new leads.Friends have raised $15,000 for information leading to an arrest.Lamar Advertising donated the billboard, which is up along I-24 at the Bell Road exit. It will stay up for a month at no cost to the family."We're hoping that people will see that as they're traveling from Rutherford County to Davidson County and they'll see it and maybe spark some knowledge," said the victim's wife, Angela Warpoole.Investigators believe Warpoole was in Murfreesboro sometime between 3 a.m. and 6 a.m. on the morning he died.Detectives say cell phone records prove he was in the Broad Street area during that time."I don't know why. Still to this day, I just don't know," said Warpoole.Anyone with information should contact detectives with the Rutherford County Sheriff's Department at 615-904-3054.