Deputies have released surveillance pictures of the suspect who grabbed the youngster from behind back on Dec. 8 at a Ross store in the Puente Hills Mall.
They say he fondled her for several seconds before her mother spotted the incident. She yelled, and he ran away.
The suspect is described as a Hispanic male, 30 to 35 years old, between 5 feet 6 inches to 5 feet 7 inches tall and weighing between 200 and 220 pounds.
If you have any information about the suspect or the incident, you're urged to call the Los Angeles Sheriff's Department's Special Victims Bureau at (877) 710-5273.