Surveillance pictures suggest the robber is an older white male, but the FBI is working on a theory that he may be a man or a woman in an elaborate mask made by the company Spfx Masks in Van Nuys.
Authorities recently served search warrants on Spfx Masks to find out who purchased the mask believed to be the one worn by the bandit.
Spfx Masks made the mask Freddy Kruger wears in the "Nightmare on Elm Street" movies.
The company said others have used their masks for illegal purposes.
KABC-TV LOS ANGELES, CA contributed to this report.