murder, criminal homicide, usually distinguished from manslaughter by the element of malice aforethought. The most direct case of malicious intent occurs when the killer is known to have adopted the deliberate intent to commit the homicidal act at some time before it is actually committed. Very often, however, the law presumes the existence of malice aforethought from the circumstances, and it does not necessarily have to be proved directly. The most clear-cut case of this presumption of malice is when the killer inadvertently murders a person other than his intended victim. Here, malice is presumed if the killer intended to inflict serious bodily injury, or if he behaved with such reckless disregard of the safety of others as to betray a "depraved heart." Likewise, a killing incidentally committed in the course of a felony (e.g., robbery or rape) is deemed murder; if the felony was accomplished by more than one person, all are equally guilty of the murder, not only the actual killer. A murder that is incidental to a misdemeanor, however, is treated as manslaughter. Most states prescribe various degrees of murder. Murder in the first degree generally is a calculated act of slaying committed with malice aforethought, often requiring aggravated circumstances such as extreme brutality. It receives the severest penalty, often life imprisonment or capital punishment. Second-degree murder is a homicide committed with malice, but without deliberation or premeditation. A homicide committed without malice (as in negligent motor vehicle operation) or in the "heat of passion" (as in a quarrel which escalates to violence) is generally considered manslaughter. In some states, certain crimes that are defined as murder of a lower degree approximate more closely the definition of manslaughter in common law. In some cases, it is difficult to determine whether malice aforethought was present; consequently the governor of a state (or other chief executive) not infrequently uses his power of commutation of sentence to revoke the death penalty, and in some states the appellate courts automatically review all convictions of murder.

Murder, Inc., name given to the band of professional killers who operated (1930-40) throughout the United States as the enforcement arm of the Syndicate, composed of the national heads of organized crime. Originally a gang of neighborhood thugs in Brooklyn, N.Y., they soon came to the attention of Louis (Lepke) Buchalter, a member of the Syndicate, who extended their activities to the national scene. With Albert Anastasia, allegedly the connection between the Troop, as the gunmen of Murder, Inc., were called, and the Syndicate, the band committed well over a hundred murders. They continued their criminal acts for years, allegedly protected by politicians, and it was not until the late 1930s with the investigations of Thomas E. Dewey that their existence came to public notice. Law-enforcement authorities led (1940-41) an assault on Murder, Inc.; it resulted in numerous convictions and several executions, including that of Buchalter. However, the mysterious death of Abe (Kid Twist) Reles, chief killer of Murder, Inc., and the state's star witness, hampered the prosecution.

Unlawful homicide of at least two people, carried out in a series over a period of time. Serial murder differs from mass murder, in which several victims are murdered at the same time and place. Criminologists have distinguished between two types of serial murder: classic serial murder, which usually involves stalking and is often sexually motivated, and spree serial murder, which is usually motivated by thrill-seeking. Cases of serial murder have been documented since ancient times. The incidence of serial murder increased dramatically in the early 19th century, particularly in Europe, though this development has been attributed to advances in crime detection and increased news coverage rather than to an actual rise in the number of occurrences. From the late 19th century serial murderers received considerable attention in the press, and their cases inspired numerous books and films. These accounts, however, tended to mislead the public by suggesting that serial murder is a common phenomenon, when in fact it represented less than 2percnt of all murders in the late 20th century.

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Popular name for an arm of the U.S. national crime syndicate founded circa 1930 in Brooklyn, N.Y., to threaten, maim, or murder designated victims for a price. Its services were available to any syndicate member anywhere in the country; many of its victims were themselves syndicate members who were killed for “business reasons.” Its principal figures were Louis Buchalter, known as Louis Lepke, and Albert Anastasia. Investigated by Thomas Dewey, it was exposed in 1940–41 by a former member, Abe “Kid Twist” Reles, who described some 70 murders and suggested hundreds more; he himself died mysteriously in the middle of the investigation.

Learn more about Murder, Inc. with a free trial on Britannica.com.

Popular name for an arm of the U.S. national crime syndicate founded circa 1930 in Brooklyn, N.Y., to threaten, maim, or murder designated victims for a price. Its services were available to any syndicate member anywhere in the country; many of its victims were themselves syndicate members who were killed for “business reasons.” Its principal figures were Louis Buchalter, known as Louis Lepke, and Albert Anastasia. Investigated by Thomas Dewey, it was exposed in 1940–41 by a former member, Abe “Kid Twist” Reles, who described some 70 murders and suggested hundreds more; he himself died mysteriously in the middle of the investigation.

Learn more about Murder, Inc. with a free trial on Britannica.com.