When it comes to mafia, gang, black ops (not the fucking video game), and other shit the "trigger man" is the one who ties up the loose ends. A dirty job but the trigger man makes sure one whistle blower doesn't mess up a well planned operation, robbery, hit, etc. If you don't have the heart to be the trigger man, there will always be a bastard out there that won't bat an eye over doing it.
Example from "The Town", Man one is Jeremy Renner, and man two is Ben Affleck in a conversation.

Man one: You uh, check on that thing, the license?
Man two: Yeah, nothin', its a dead end. We are all set.
Man one: So no need to remove her from the equation?
Man two: What are ya a Trigger man now?
Man two: Just loose ends kid.
by CTU_FieldAgent200 December 5, 2011
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