The crime of homicide is tragic for everyone involved: the victim, their family and friends, and even the perpetrator. The term homicide means the killing of one person by another. Some homicides can be ruled legal, such as self defense or when a police officer kills a suspect in the line of duty. Homicides that are criminal, however, are called unlawful homicides such as murder or manslaughter.

Murder is the unlawful killing of a person committed by the perpetrator with "malice aforethought," which is the intent to do harm with a disregard for life. Malice aforethought must be proven by the prosecution for a murder charge. The defendant must have inflicted serious bodily harm to the victim or used behavior that demonstrated reckless disregard for the victim’s life.

There are different degrees of murder. First degree murder is the most serious and the crime is considered especially immoral or dangerous. First degree murder is intentional. The killer must have had premeditation to commit the crime and could have made plans for the crime. If the killing occurs during the commission of a felony, it can also be considered murder in the first degree. Using explosives for a murder can be considered first degree since there is a presence of planning when using bombs or other explosives; they also have the potential to kill many innocent people. A first degree murder conviction can result in life in prison or the death penalty in some states. Second degree murder is charged when the crime is considered somehow less immoral than a first degree murder. Some defendants convicted of second degree murder can eventually be released from prison on parole.

Manslaughter is less serious than murder. It is still an unlawful killing but it does not involve malice aforethought. Since the law recognizes that manslaughter is less morally reprehensible than murder, the punishments can be less severe. Voluntary manslaughter is also known as a "crime of passion" when the perpetrator commits the crime in some type of emotional rage. The defendant is usually a reasonable person in every other circumstance and did not plan to commit a killing. Involuntary manslaughter is when a death occurs as a direct result of someone’s reckless behavior.