No, someone can hunt down THAT killer and give him a citation for bravery, and thank him for delivering better justice than the 'slappy-hands, bleeding hearts" system ever gave.
Yeah yeah, whatever. Evil begets evil... the best way is to let them serve their punishment, whatever the law decides. The LAST thing you want to do is REWARD unrepentant, merciless murderers who deliberately break the law, KNOWING the full extent of their actions. What sort of message would that send out to society? If the courts dont deal out a punishment long enough, then its OK to take their lives?
If the 2 do get murdered, then the killers should serve full term MURDER charges, for pre-meditated murder.
They wouldnt have been released if the judge wasnt satisfied they were repentant. Give them a chance. Its only fair. If they blow that chance, then they will get what they deserve.