Lepper was near White Avenue when she was shot in the head by someone who was in another vehicle.
Her heartbroken relatives are appealing for help to find her killer.
"She would of forgiven this person even though they had committed this terrible crime against her. She would of forgiven them. She was just a loving lady," said Lepper's sister, Terri Evens.
The Bureau of Alcohol, Tobacco, and Firearms is working with the CHP and is offering a $10,000 reward for information leading to an arrest.
"We will not tolerate any acts of violence like this on our freeways. And we will not let this incident go and let this incident be in vein," said ATF agent John Torres.
Police say that they have no witnesses, but did receive a number of tips early on.
The family has endured a lot of tragedy. Lepper's 18-year-old son had died just a year earlier in a traffic accident. And they had been preparing to celebrate a special event.
"She was killed just one month before the highly anticipated birth of my son. It was something she was so looking forward to. Just days before her death we were making last minute plans for my baby shower," said Lepper's niece, Whitney Nielson.
Anyone with information is asked to call the CHP at 800-TELL- CHP or 800-835-5247.