A key witness in a double-murder case in Antioch, Calif., is a former rental car clerk who oversaw and used her employee discount on the rental of the minivan that was used to kill a drug dealer, according to the San Jose Mercury News.

Katrina Fritz, a former rental car clerk who worked at Fox Rent-A-Car at Oakland International Airport, told the newspaper she could have helped police solve the case early in the investigation but refused because she feared for her safety.

The case involves two men accused of killing a drug dealer in Antioch, and later a 40-year-old mother in Oakland, in an attempt to hide the original slaying.

Fritz agreed to help in the case after she was granted immunity. Her testimony has helped prosecutors piece together a tale that involves the two suspects allegedly running over one man with the rented minivan and then killing April Bradley of Berkeley, Calif. Prosecutors say the suspects feared Bradley, who rented the van for the pair, would be able to pin the Antioch slaying on them.

Evidence in the case has shown that Bradley rented the minivan for one of the suspects because he did not have a driver’s license or credit card necessary to get the vehicle.

Fritz, whose boyfriend was friends with the two suspects, found herself in the middle of the investigation when police realized she was the clerk who oversaw the minivan rental.

During testimony, Fritz detailed what she thought was an innocent plan to give friends a discount on a car rental had turned into a double-murder case that threatened her life.

Fritz said she agreed to rent a car to one of the suspects using her employee discount rate at the request of her boyfriend. Fritz said she didn't think anything about the rental until three weeks later when her co-workers told her that Antioch police had confiscated the rental car, found blood on its undercarriage and were requesting to talk to her.