It’s been more than a year since a 24-year-old woman was shot to death outside the car rental business where she worked. But the case of Monique Marlowe’s homicide remains unsolved, police said.

On Thursday, Hertz increased the reward to $50,000 for information leading to the arrest and conviction of the person responsible, and Gwinnett police are hoping for new clues in the case.

“It is possible that witnesses have not yet come forward, and also possible that witnesses did not realize that what they saw is important,” Cpl. Jake Smith said in an emailed statement. “We are hopeful that the increased reward will encourage anyone with information to come forward.”

Marlowe, 24, of Duluth, was shot and killed on the afternoon of Sept. 21, 2012, as she was cleaning a car in the back of the Hertz location on Satellite Boulevard. Police believe Marlowe was approached by a man who shot her once and left the area.

Marlowe, a 2009 University of Georgia graduate, was found wounded by her co-workers and taken to Gwinnett County Medical Center, where she died.

Following Marlowe's death, Hertz offered a $25,000 reward in the case.

Anyone with information should call detectives at 770-513-5300 or contact Crime Stoppers at 404-557-8477.