DULUTH, Ga -- It was a murder that never made sense and still doesn't more than a year after it happened. Monique Marlowe, 24, of Duluth, was shot and killed at her job September 21, 2012. Thirteen months later, police are hoping a $50,000 reward will encourage someone with information about the case to come forward.

Marlowe was shot and killed behind the Hertz rental car company on Satellite Boulevard near Gwinnett Place Mall. She was cleaning a rental car when someone approached her and shot her. Before she died, she was able to give police a very vague description of the suspect. "She said it was a black male wearing a light blue shirt and 'I didn't know who he was'," said Gwinnett County Police Corporal Jake Smith.

Thirteen months later, police and her parents, Dan and Maria Marlowe, still don't know who killed her. "Why would someone do that?" Dan Marlowe asked. "It just baffles us."

The rental car company is in a very busy area and the murder happened during the evening rush hour, the busiest time of day. Monique Marlowe's body was found by co-workers partially inside the car she was cleaning.

"She had no enemies, she was not participating in any kind of illegal activity," Cpl. Smith said. "She was purely a victim of whatever happened there and we would very much like to be able to solve this crime."

A motive has been elusive. Her parents say a clue might be her favorite necklace from Disney that she loved to wear. They said they couldn't find it after she was killed. "Possibly the person who did this may have snatched it, just grabbed it," Her father said.

Police said the motive may have been robbery. "She was not wearing it when she was discovered and no one can say whether or not she was wearing it earlier in the day," Cpl. Smith said.

Dan Marlowe said he doesn't think the killer will ever turn himself in because he doesn't care. "He should feel guilty about a beautiful life that's destroyed," he said.

Police believe someone may have heard or saw something they didn't realize was important and they're hoping the sizeable reward of $50,000 will encourage them to come forward.

We're hopeful that maybe that (reward) will attract some attention and maybe we'll get a tip," the victim's father said. "I won't give up. I'll keep trying. I will not give up."

Police are asking anyone with information about the case to call Crime Stoppers Atlanta at 404-577-TIPS (8477).