<P> Nicholson , however , wanted the film to have `` something a little more '' than the usual gangster film , and screenwriter Monahan came up with the idea of basing the Costello character on the famous Irish - American gangster Whitey Bulger from Boston . This gave the screenplay an element of realism -- and also an element of dangerous uncertainty , because of the wide - ranging carte blanche the FBI gave Bulger in exchange for revealing information about fellow gangsters . A technical consultant on the film was Tom Duffy , who had served three decades on the Boston Police Department , particularly as an undercover detective investigating the Irish mob . </P>
<P> Nicholson , however , wanted the film to have `` something a little more '' than the usual gangster film , and screenwriter Monahan came up with the idea of basing the Costello character on the famous Irish - American gangster Whitey Bulger from Boston . This gave the screenplay an element of realism -- and also an element of dangerous uncertainty , because of the wide - ranging carte blanche the FBI gave Bulger in exchange for revealing information about fellow gangsters . A technical consultant on the film was Tom Duffy , who had served three decades on the Boston Police Department , particularly as an undercover detective investigating the Irish mob . </P>
who is the movie the departed based on
who is the movie the departed based on
Irish - American gangster Whitey Bulger
Irish - American gangster Whitey Bulger