Malefactors are the encarnations of various forms of death and execution, and seem to have sentient characteristics. In particular those which bear great wrong doing and vengeance, or otherwise the suffering incarnate of the victims. They attack each other on sight and only work together to attack people only to continue fighting each other immediately afterwards. They are most likely the actual souls of the victims themselves (or their executioners) to seek vengeance (or ease their suffering) on others indiscriminantly. Their behavior is related directly to how, and why they're killed and whether it's the victim or the killer.
They're all extremely deadly to the average person and unless they're capable in some aspect (they have a gun, and good aim) they'd end up dead shortly after an encounter. They have appeared in other places other than Carnate, but in very small numbers, and hatred is the direct cause of their appearance.