Murder is classified as unlawful taking of a life, hence a capital offence and in most statutes around the world, attracts either life in prison, execution by lethal injection, firing squad or simple hanging.
In centuries past, when religious edicts governed the pulse of society and were the sole barometer of integrity, justice and governance, religious book-based laws recommended an eye-for-an-eye, life-for-a-life as a suitable and widely accepted form of retribution and deterrence.