In his article Heat: the final waltz of the cyborgs, Lawrence Russell provides as much of a detailed psychological analysis as a film review. About “Waingro,” the character played by Gage, he begins:
“… we’re all quite comfortable with [the bank heist], except for the unfortunate executions of the three Brinks guards, precipitated by the cold-blooded killing of one by the outsider, Waingro (Kevin Gage). Waingro is a thrill-killer, a sociopath who kills as part of his sexual expression. Later, when he murders the sixteen year old black prostitute you suspect he’s acting as an apostle of white power as he has a swastika tattooed on his stomach. When McCauley catches up with him in the final stanza, shoots him between the eyes, it’s natural justice for the Brinks Guards and the prostitute as much as it’s a revenge for his betrayal.”
See the complete article at Film Court. Watch out for major spoilers.