Sheikh `Abd al-Wahhâb al-Turayrî, former professor at al-Imâm University in Riyadh
This is a case in which a hearing is needed where both parties must present themselves before the courts. You have to inform the inheritors of the deceased to pursue their claim in the legal court in the place where the killing took place . If their claim is confirmed, the killer should receive the legal punishment.
The Prophet (peace be upon him) said: “Whoever has one of his relations murdered has the choice either to receive compensation thereto or have the killer killed.” [Sahîh al-Bukhârî (2434) and Sahîh Muslim (1355)]
The relatives of the murder victim have the right to appeal to the courts for the murderer to be executed in retribution for the murder. However, if the country in which the murder took place does not apply Islamic Law, then the relatives of the victim should be patient and submit their affair to Allah. They may not kill the murderer on their own. This will cause trial and mischief in the society. It could very well result in greater evil.
Whatever happens, take comfort in Allah’s words: “If a man kills a believer intentionally, his recompense is Hell, to abide therein (for ever): and the wrath and curse of Allah are upon him, and a dreadful chastisement is prepared for him”.
And Allah knows best.
Source: Islam Today