What is the ruling on one who kills himself as a form of retribution, when he deserved to be killed?

Killing oneself is one of the gravest sins forbidden by Allah. The perpetrator is threatened with severe punishment in the Hellfire, as mentioned in the Holy Qur'an and the Sunnah of the Prophet. Retribution is a right of the victims' guardians (awliya' al-dam), and the killer is not permitted to take it upon himself by suicide, because it does not achieve the legitimate objectives of deterrence and dissuasion, nor does it heal the hearts of the victims' guardians. Even someone whose blood has been declared lawful to shed (muhaddar al-dam) according to Islamic law is not permitted to kill himself, and his killing himself is not considered an expiation for his crime.