As an example suggestion: a high combat rank player in a combat capable ship boils a low combat rank player in a trade vessel. In addition to a bounty, the murderer is unable to dock at high security systems and suffers an increased insurance premium excess for an amount of time.
Pirates make little to no money as is. If you make the penalties too great, nobody will pirate any more. As it is, traders have little to no penalty for trading due to the huge income they can generate relative to the pirate.
Forgive me if I am confused on this matter, but wouldn't a Pirate especially a known notorious pirate, wouldn't want to dock or be in a high security system anyway?
To me, this seems like a correct behavior and mechanic to put on a Pirate.. They would be able to sell only at un-allied or Anarchy systems. I don't see the point of being able to pirate someone, say like in a federation system, then jump to a neighboring federation system and sell items and repair your ship with zero repercussion(s).
Of course they should also make anarchy systems more interesting, but black markets ONLY in Anarchy systems too. Make they payouts for dealing with them higher as well. High risk, high rewards. Offer bonus incentives for NOT killing or forcing the target to Self Destruct!
What I am trying to get at is, make Pirating, more - for lack of a better word - Piratey. If you end up getting allied with Anarchy systems and become a notorious Pirate offer them a free skin at the station so they can be painted as a pirate too (if they want to be).
Murder someone (even at lower rank) Yes make it harder for them to move around and they HAVE to be forced to use Anarchy Systems only. Make a higher spawn of Bounty Hunters.. Make it so Bounty Hunters get better rewards for killing a notorious murderer. Accident or not, you still killed them.