A source, whose name was not reported, also refused to tell The Hollywood Reporter the former employee's name.
NBC's "Today Show" aired the 911 call March 27, but critics said the network's choice to edit out elements of the script make it appear as though Zimmerman's motivation for shooting Martin was based on his skin color, the Reporter said Friday.
In the original call, Zimmerman says, "This guy looks like he's up to no good. Or he's on drugs or something. It's raining and he's just walking around, looking about."
The dispatcher asks, "OK, and this guy -- is he white, black or Hispanic?"
Zimmerman tells the dispatcher, "He looks black."
The NBC version omitted the dispatcher's question and Zimmerman is heard saying, "This guy looks like he's up to no good. He looks black."
NBC said March 31 it had launched an investigation into the matter.
"We will be taking the necessary steps to prevent this from happening in the future and apologize to our viewers," NBC said Tuesday.