“He could be charming. He could be ruthless. He was like a cobra—you never knew where he could strike,” says director Scott Cooper (Crazy Heart) of notorious crime boss Whitey Bulger, played by Johnny Depp in Black Mass (out Sept. 18). The film tells the true story of how Bulger, the brother of a state senator (Benedict Cumberbatch), became the most feared gangster in Boston while simultaneously serving as an FBI informant to take down the Italian Mafia.

Depp may not seem the obvious choice for the role of the blue-eyed, fair-haired Bulger, but once he was in character, the effect was palpable. “A lot of people on set knew Whitey intimately,” says Cooper. “They got chills at the resemblance. Some of them couldn’t even look at him.”

Image Credit: John Tlumacki/The Boston Globe via Getty Images; Claire Folger

To re-create Bulger’s intimidating style and persona, Cooper and Depp pored over surveillance tapes and old FBI photographs. In the scene (shown above) Depp’s Bulger walks down the street after killing a man in a parking lot. “He murdered him in front of numerous witnesses in broad daylight,” Cooper says. “In a word, Whitey was brazen.”

And so was Depp in his portrayal. “It’s easy to be the mustache twirling villain but this performance couldn’t be further from that,” the director says. “He is truly gifted.”

Image Credit: Claire Folger