As the question was asked (And its a good one) I will provide some clarification
on The relationship between NPK characters, Voodoo, and freepk areas.
It is NOT illegal for you to make a voodoo doll of a character that you killed
in freepk regardless of PK status. This means that if an NPK kills a PK in freepk, they may
also make a voodoo of the PKer