Venger wrote:
Anybody ever wonder why gang members that commit multiple murders aren't usually referred to as "serial killers"?

Completely different, IMO, gang violence is exactly that, gang violence.
Gang violence and people that kill over money, I find really boring. There's no psychology there, other than these people value money more than they value human life.
With gangs it seems to be a territorial/ dominance thing, or something regarding money or drugs.
Serial killers seem to have little to no empathy, they can pass lie detector tests and generally feel no guilt, and often keep "trophies" of their victims. They generally have the same MO, often leaving little signatures to help identify them as the killer, for some killers it seems to be almost like a game, or a hobby. The interesting thing, at least to me, is no one really knows if a person can be born without empathy, or if they lost it somewhere in their young environment.
There are serial killers that grew up with apparently perfect, uneventful lives, and killers who grow up with severe abuse, so how can anyone really know?
That kind of psychology can help you realise that even you may unwittingly know a serial killer.