Authorities sought help from the public in identifying the girl, releasing a sketch of the victim during a press conference Wednesday. They described the girl as being between the ages of 8 and 13, 4 feet 5 inches tall and weighing 55 pounds.
An autopsy was performed Thursday. No other details were released.
MORE: Community holds vigil, seeks answers about girl found dead on Hacienda Heights trail
Her body was partially inside a duffel bag when it was found Tuesday morning by county workers clearing brush in the area. Authorities believe she was dumped sometime Sunday evening.
Anyone who saw a vehicle parked alongside Hacienda Boulevard on Sunday or has information related to the case is asked to contact the Los Angeles County Sheriff's Homicide Bureau.