Simone Walker, 34, was hit by a car as she crossed Avenue L at 32nd Street West at 7:43 p.m. on March 19. The vehicle did not stop.
Detectives say so far, no witnesses have come forward to help identify the vehicle involved.
"We are a little perplexed as to why nobody's come by and seen anything," said Sgt. Dave Jennings of the L.A. County Sheriff's Department.
Jennings said the roadway is moderately traveled, and surveillance video showed that there was a moderate amount of traffic at that hour.
The L.A. County Board of Supervisors is offering the $10,000 reward for information that leads to an arrest and conviction.
"We just need some type of closure. Who would do this and just keep going?" said the victim's sister Michulae Walker. "That's heartless, and I know whoever this is has a mother, has a daughter, a sister. How would they feel?"
Anyone with information is urged to call Crime Stoppers at (800) 222-TIPS.