Investigators said evidence from her car and the structure where she parked led them to conclude the 26-year-old was murdered.
Police said it wasn't a random attack. The killer targeted Le.
Detectives have questioned persons of interest, including Le's good friend Giselle Esteban. She was arrested, but was later released.
She was last seen May 27 when she went to get something out of her car in the parking garage of a hospital in Hayward.
Le's family is still hopeful she is alive. Her father said that he feels Hayward police have given up on finding his daughter alive without providing conclusive evidence to support their decision Monday to reclassify the case as a homicide.
An official with the police department said that earlier reports that the family has been critical of the department were understandable, but that investigators have a reason for holding some details back.
The Associated Press contributed to this report.