What is the ruling regarding the killer and the killed in cases of intentional and unintentional killing?

Deliberately killing a Muslim is a grave sin and a tremendous crime, and its punishment is Hellfire and eternal dwelling therein, the wrath and curse of Allah, and a great torment, as stated in Surah An-Nisa, Ayah 93.

As for accidental killing, it entails blood money (diyah) and expiation (kaffarah): freeing a believing slave and blood money to be handed over to the deceased's family, or fasting for two consecutive months for whoever cannot find [a slave to free], as stated in Surah An-Nisa, Ayah 92.

For a deliberately murdered person, his guardians have the right to retribution (qisas) from the killer, unless they forgive or accept blood money.