Why is Holder going after Mafia guys?

Why is Holder going after Mafia guys?
shouldnt we be more worried about terrorists and inner city gangs who dont give a dam about human life, rather than some criminal organizations who do very little damage to the general public and more to themselves?Like in all honesty, why are half of those guys in GITMO not being executed, yet he wastes his time on nailing guys who are really not a big threat to society as a whole. Anyone know why terrorists are getting more rights than Mafia guys?