Homicide is the act of one person causing the death of another person. Not all homicides are murder—some are manslaughter due to mitigating circumstances—and some are lawful when justified by an affirmative defense such as self-defense or insanity.

Criminal homicide generally involves (1) intent to cause death or serious bodily injury, or (2) negligence that causes the death of another person. Criminal homicide committed with the intent to cause death or serious bodily injury is generally charged as the criminal offense of murder (committed with intent and with premeditation or malice) or as voluntary manslaughter or second degree murder (committed with intent but without premeditation or malice).

And criminal homicide caused by negligence is generally charged as the criminal offense of involuntary manslaughter—for example, when a person is driving recklessly or speeding and hits another motor vehicle or pedestrian, causing the death of the other motorist or the pedestrian. A person driving a motor vehicle while intoxicated by drugs or alcohol who hits another motor vehicle or pedestrian, causing the death of the other motorist or the pedestrian, may be charged with involuntary manslaughter, or with a more specific offense like intoxication manslaughter or vehicular homicide—depending on applicable state laws.

Criminal homicide laws vary from state to state—including the names, degrees of severity, and punishments. These laws are generally found in a state’s statutes—often in the penal or criminal code.

In New Mexico, homicide is defined as the killing of one person by another and can be categorized as either lawful or unlawful. Unlawful homicide includes murder and manslaughter, which are differentiated by the presence of intent, premeditation, and malice. Murder is typically charged when there is an intentional killing with premeditation or malice aforethought. It can be classified into different degrees, with first-degree murder being the most severe, often involving deliberate planning. Voluntary manslaughter, on the other hand, is a killing that occurs in the heat of passion or during a sudden quarrel without prior intent to kill. Involuntary manslaughter in New Mexico occurs when a death is caused by negligence, such as reckless driving or driving under the influence of drugs or alcohol. The specific charges and penalties for homicide offenses are detailed in New Mexico's statutes, particularly within the criminal or penal code. These laws outline the elements required for each offense, potential defenses such as self-defense or insanity, and the associated punishments, which can range from fines and imprisonment to life sentences or even the death penalty under certain circumstances.