Homicide is the killing of one person by another. Not all homicides constitute crimes, however. Certain exceptions, such as some killings in self-defense, are not crimes.
Criminal homicides range from involuntary manslaughter to first degree murder, with gradations along the spectrum of possible charges. Factors which push a killing from one category to another include whether the killing was premeditated, whether the killer intended to cause death, whether the killer acted on purpose when causing death, and if not, whether the killer acted with criminal negligence, recklessness, or with obvious disregard for human life.
Different states draw slightly different lines between the various types of manslaughter and murder charges. Sentences handed down upon conviction vary widely between the different charges, and can include life without the possibility of parole, and the death penalty in most states, for first degree murder convictions.
•First Degree Murder - The highest level of criminal homicide, typically reserved for willful and premeditated killings.
•Second Degree Murder - Most often voluntary but without premeditation -- often seen as the middle ground between voluntary manslaughter and first degree murder charges.
•Voluntary Manslaughter - Generally a killing which was voluntary, but done in the heat of the moment.
•Involuntary Manslaughter - A killing that is not on purpose, but results from criminally reckless or negligent behavior, or from low level criminal activities