“deiyezooger: One of my questions (the last one) was why. If an unintentional killer can be killed by the victims family why can’t an intentional killer (without the requisite warning that would allow the death penalty) not be killed by the victims family?”
The point of being aloud to kill an unintentional killer is just a means to force him into galos (ir miklat) as a kaparah for killing b’shogeig.