The incident happened last Tuesday just before 1 p.m.
The employee - who has worked at the Chevron on Atlantic Boulevard for 20 years - was knocked to the ground and suffered a serious head injury.
Surveillance video shows a man in a pink shirt taking a drink from a store cooler. When he begins to walk out without paying, the Chevron employee is knocked to the ground. Moments later, another employee rushes to help the injured man.
According to investigators, the worker remains hospitalized in critical but stable condition.
Authorities are asking anyone who recognizes the man in the pink shirt to contact East L.A. sheriff's deputies.