KNOXVILLE, Tenn. (WVLT) -- Each day, thousands of people driving near Knoxville see a billboard that shows a young, smiling, woman, and asks the question "who killed Gina?" In February of 2009, Gina Thacker's body was found in her car at the Valley Oaks Apartments in North Knoxville. Police say she had been shot to death.

Her mother, Cynthia Thacker, said the pain of losing her daughter in such a violent way, hasn't gotten any easier. "She had this beautiful thick head of hair, and sometimes she would lay her head on my lap and i would rub my hand through it. I can almost feel that sensation of my fingers going through her hair, I miss that."

Investigator Jeff Day with the Knoxville Police Department, told us that out of hundreds of interviews, only one potential witness has stepped forward. "A juvenile told us he was on the computer that night, heard a noise, looked out, and saw a guy running away. That's it. It's frustrating."

The physical evidence is limited as well. Police recovered the bullet, which is now part of a national data base. So far, there have been no matches. A set of fingerprints found inside the car also hasn't been matched. Cynthia says the big break in this case is only going to happen if someone steps forward. "Sometimes I think, wake up, its not real. It really cant be real. Then I realize it is this is my life now."

There is a 25 thousand dollar reward for information leading to the conviction of Gina Thacker's killer. If you have any clues, please call the Knoxville Police Department tip line at (865) 215-7212.