Voluntary manslaughter in a country that does not apply Shari`ah

Q: Please give us a Fatwa (legal opinion issued by a qualified Muslim scholar) regarding a man who testifies that there is no god but Allah and that Muhammad is the Messenger of Allah, but he has intentionally killed another person in a casual dispute. Since we live in a country that does not apply Hudud (ordained punishments for violating Allah’s Law), we would like to pose the following questions: (Part No. 21; Page No. 210) 1. Is it permissible for the family of the victim to murder the killer? Why?2. Is it permissible for the family of the victim to take a Diyah (blood money) from the killer since he is a Muslim? Or has the killer turned into a Kafir (disbeliever) by intentionally killing another Muslim? Does the Ayah (Qur'anic verse) mentioned in Surah (Qur'anic chapter) Al-Furqan on manslaughter apply to this case?3. Is there a certain value for the Diyah? There is a lot of argument about this issue.We would be grateful if you would reply as quickly as possible so that we can guide each party to the right way as set by Shari`ah (Islamic law).

A: First, it is permissible for the heirs of the victim to ask the ruler to have Qisas (just retaliation) against the person who has intentionally killed their relative. Allah (Exalted be He) says: And do not kill anyone whose killing Allâh has forbidden, except for a just cause. And whoever is killed wrongfully (Mazlûman intentionally with hostility and oppression and not by mistake), We have given his heir the authority [to demand Qisâs, - Law of Equality in punishment - or to forgive, or to take Diyah (blood money)]. But let him not exceed limits in the matter of taking life (i.e he should not kill except the killer). Verily, he is helped (by the Islâmic law). Second, the Diyah must be paid if murder is committed either intentionally or unintentionally and the heirs or one of them pardons the killer and asks for the Diyah. A Muslim cannot be described as a Kafir because of committing premeditated murder. Allah (Exalted be He) says: And those who invoke not any other ilâh (god) along with Allâh, nor kill such person as Allâh has forbidden, except for just cause, nor commit illegal sexual intercourse - and whoever does this shall receive the punishment. The torment will be doubled to him on the Day of Resurrection, and he will abide therein in disgrace; Except those who repent and believe (in Islâmic Monotheism), and do righteous deeds; for those, Allâh will change their sins into good deeds, and Allâh is Oft-Forgiving, Most Merciful. (Part No. 21; Page No. 211)  Third, the value of the Diyah is determined by the judge according to the type of murder, whether it is a premeditated murder, a quasi-deliberate homicide, or an involuntary manslaughter.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.