User:Lord Gøn/Intro

This is a partial list of a certain type of mass murderer, for convenience's sake in the following referred to as rampage killers, organised by death toll, further divided into several subsections. The intention behind this list is not to provide a complete overview of incidents, otherwise it would grow out of proportions very soon, but concentrates on cases that stick out by their sheer number of victims. Thus, this list will contain rampage killings with one or both of the following features: As there's often conflicting information about the number of dead and injured, which do not include the perpetrators themselves, in cases of uncertainty a range is given.
 * Cases with six or more dead (excluding the perpetrator)
 * Cases with a double digit number of victims (dead plus injured)

Carving a giant - Definition of the rampage killer
Until the early 1980s the term mass murder was used to describe any, often very dissimilar incident in which a number of persons were killed. Neither was there made a differentiation between crimes as Whitman's shooting, serial murders or spree killings, nor other forms of mass murder like the Holocaust or the Jonestown mass poisoning. Even accidents like the Bhopal disaster were termed as mass murders.

In colloquial language the term mass murderer is commonly used to describe anyone who intentionally caused, directly or indirectly, the death of many people. This rather vague definition is applied on states, governments, organziations, groups or persons who order genocides, massacres, war crimes, terrorist acts or similar deeds and their perpetrators, as well as individuals who do not act on behalf of higher institutions, but out of their own personal motivations, like school shooters, spree killers, arsonists and even serial killers.

Due to the surge in widely publicized serial killings, beginning in the late 60s, a classification for mass murders, serial murders and spree killings was developed. The cases were distinguished by the amount of time between the murders. Mass murder was classified as incidents in which one or more offenders killed a number of victims over a short period of time. No unitary definition for mass murder exists though.

mass murder should be defined as offenses in which multiple victims are intentionally killed by a single offender in a single incident. (time and distance are possible limiting criteria for the concept of a single incident) (offenses occurring within a 24-hour interval) (ignore location or distance in the definition) define mass murder as the willful injuring of five or more persons of whom three or more are killed by a single offender in a single incident Whereas serial murders occurred over an extended period of time, mass murders were classified as incidents in which one or more offenders killed a number of victims (at least 3 or 4) over a short period of time (i.e. minutes or hours) mass murder defined as the killing of three or more people in one place at one time According to the USA Bureau of Justice Statistics mass murder is defined as "the murder of four or more victims at one location, within one event."
 * Different definitions of mass murder
 * Dietz
 * Duwe
 * Petee

usually the senior man of the house, who is depressed, paranoid, intoxicated or a combination of these. He kills each member of the family who is present, sometimes including pets. He may commit suicide after killing the others, or may force the police to kill him. who are preoccupied by firearms and commit their raids after long deliberation. The murderer may force the police to kill him. who employ techniques allowing themselves the possibility of escape before the deaths occur. Examples include those who bomb buildings or vehicles on which they are not traveling, who set arson fires, or who tamper with food or products, as in the Tylenol poisonings. While the offender may have one or more particular victims in mind, he considers the indiscriminate killings of bystanders an unimportant cost in relation to the enhanced probability of escape provided by these methods. As with bombings generally, the most common motives are anger or revenge toward people or institutions, but extortion, insurance fraud and ideological motives are also observed.
 * Classifications of mass murder
 * Dietz
 * Family annihilators
 * Pseudocommandos
 * Set-and-run killers
 * Holmes & Holmes
 * Kelleher
 * perverted love
 * politics and hate
 * revenge
 * sexual homicide
 * execution
 * psychotic
 * unexplained
 * mass murder by intention
 * Petee
 * Fox/Levin
 * Power
 * Revenge
 * Loyalty
 * Profit
 * Terror
 * National Center for the Analysis of Violent Crime
 * classic mass murderer
 * family mass murderer
 * spree killer

Stereotype: deranged and/or disgruntled white male, in his thirties or forties, who often has a fascination with guns, and who usually committs suicide at the conclusion of the murder event. In the late 1980s a stereotypical view of the mass murderer began to emerge due to massive media coverage of some cases. Lack of legal term, denominated as public mass shootings, rampage killings or shooting/stabbing sprees.
 * Stereotypical image of the mass murderer

Western media mass murderer stereotype, shaped by very few high-profile cases (Whitman, Huberty, Hennard, Unruh, Ryan, Sherrill, Harris & Klebold) General: middle-aged white male loner and weapons fanatic with a grudge against the whole world Specific:
 * berserk gunman dressed in camouflage running through the streets or walking into a restaurant, shooting people at random
 * disgruntled employee killing his co-workers
 * teenage loner, addicted to violent video-games, shooting up his school

Hempel, Levine, Meloy, Westermeyer: sudden mass assault by a single individual (SMASI)

Though in most cases the weapons of choice are guns and rifles, especially in countries with restrictive gun laws knives, machetes, axes and the like are commonly used.

Specifics rampage killings vs. other forms of mass murder

Orignial definition of mass murder covering a broad variety of deeds

Jens Hoffmann: Amok - Ein neuer Blick auf ein altes Phänomen So far no integrative definition (maybe it is assumed that the term is self-explaining), categorisation often dubious (put crimes together that might be similar only at first glance), limits of victim numbers arbitrary Classification by Dietz not widely adopted, except "Pseudocommando"-type Definition by the "National Center for the Analysis of Violent Crime": classic mass murderer, family mass murderer, spree killer, often not consistent The amok-phenomenon: Definition by the "American Psychiatric Association" Myths about amok Leaking

Fox/Levin
Power, Revenge, Loyalty, Profit, Terror
 * FBI's Behavioral Science Unit (BSU) defined mass killings (or massacres) as homicides involving the murder of four or more victims in a single episode
 * Classification by motivation:

Dietz
which they pursue in part for this purpose. other than homicide, including the number of victims per incident up to the category of four or more victims. For all violent criminal incidents in 1983, 88.5% involved one victim, 8.9% two victims, 1.7% three victims and 1.0% four or more victims. victims in a single incident. of the house, who is depressed, paranoid, intoxicated or a combination of these. He kills each member of the family who is present, sometimes including pets. He may commit suicide after killing the others, or may force the police to kill him. of escape before the deaths occur. Examples include those who bomb buildings or vehicles on which they are not traveling, who set arson fires, or who tamper with food or products, as in the Tylenol poisonings. While the offender may have one or more particular victims in mind, he considers the indiscriminate killings of bystanders an unimportant cost in relation to the enhanced probability of escape provided by these methods. As with bombings generally, the most common motives are anger or revenge toward people or institutions, but extortion, insurance fraud and ideological motives are also observed.
 * Subject understudied due to low frequency of occurance
 * offenders see headlines as one of the predictable outcomes of their behavior,
 * term mass murder applied to dissimilar events like Whitman's shooting, Jack the Ripper, Jonestown mass poisoning, abortion policy, Holocaust or the Bhopal disaster
 * mass murder should be defined as offenses in which multiple victims are intentionally killed by a single offender in a single incident. (time and distance are possible limiting criteria for the concept of a single incident) (offenses occurring within a 24-hour interval) (ignore location or distance in the definition)
 * number of victims required for the designation mass murder is a more arbitrary matter, but one with important implications for the characteristics of the class so defined. For example, the proportion of mass murder victims who are relatives of their killers is determined by the number of victims required in the definition.
 * The Bureau of Justice Statistics publishes annual survey data on criminal victimization
 * define mass murder as the willful injuring of five or more persons of whom three or more are killed by a single offender in a single incident.
 * Paranoid symptoms of some kind have been evidenced by all of the men who have killed 10 or more victims in a single incident in the United States.
 * Depressive symptoms predominate among those who kill more than three but fewer than 10
 * Family annihilators, usually the senior man
 * Pseudocommandos, who are preoccupied by firearms and commit their raids after long deliberation. The murderer may force the police to kill him.
 * Set-and-run killers, who employ techniques allowing themselves the possibility

Petee
Public perception of mass murder shaped by some widely publicised sensationalistic cases (Huberty, Purdy, Lepine, Hennard) (people think of killers who suddenly go berserk or run amok when asked about mass murder) research on mass murder relatively limited, most studiey focused on the stereotype "anger/revenge" type of offender: motivated by vengeance, plans offense; target sometimes specific person or place, sometimes diffuse, often convenient, suffer more likely from mental illness and are more likely to commit suicide Characteristics like ae, race, offender background and context of the offense vary greatly Far more common than the anger/revenge type are mass homicides related to family arguments, or from the commission of another felony.
 * mass murder defined as the killing of three or more people in one place at one time
 * Stereotype: deranged and/or disgruntled white male, in his thirties or forties, who often has a fascination with guns, and who usually committs suicide at the conclusion of the murder event.
 * Public image of mass murder not very accurately describing most cases.
 * Mass murder extremely diverse phenomenon, motivationally and situationally
 * Domestic related cases represent most frequent form of mm (estimated: almost half of total, likely higher), often related to family disputes or marital problems
 * Felony related mm: offenders younger than stereotype, rarely suicide, often (over 50%) more than one offender involved
 * Some definitions preclude cases with more than one offender

Petee: DIFFERENTIATING FORMS OF MASS MURDER
Dietz (1986) early attempts to classify incidents of mass murder. mass murder offenders typically fall into one of three categories: family annilhilators – who target family members, usually in a home setting; pseudocommandos – who fancy themselves as military types, have a fascination with firearms, and frequently plan their offense with some detail; and, set-and-run killers – who murder more remotely (i.e., with bombs or poison) so as to remove themselves from the crime scene before the murders occur, and allow for the possibility of escape. Holmes and Holmes (1994) built upon Dietz's typology provided two additional categories: disciples – who are unduly influenced by a charismatic leader to kill; disgruntled employees – who retaliate for what they feel was bad treatment from their employer. As can been seen from the expanded typology above, it makes use of several bases for classification, mixing together motivation, the specific relationship between the victim and the offender, and technique for killing. Unfortunately, this leaves a system that is neither mutually exclusive nor exhaustive in describing cases of mass murder. There are several offender, for example, who would fit in more than one of the categories. On the other hand, there are a number of offenders who do not fit into any of these offender types. anger/revenge – diffuse target: actually follows one of two different victimization patterns. In the first type of pattern, the offender targets specific groups or categories of people, although specific persons are not targeted. In this pattern, the offender usually has a deep hatred for the group in question. The second pattern for this category involves an offender who simply lashes out at whoever is available as a target. direct interpersonal conflict: ontrasts with the anger/revenge forms of mass murder in that the former involves a conflict situation that is more immediate – as opposed to the long-simmering anger typical of the latter. These cases usually result from a relatively trivial dispute, and the offender is often a volatile person who reacts violently to the conflict situation. Gang-motivated mass murder: incidents such as drive-by shootings or gang confrontations. These murders often have a dispute element as in direct interpersonal conflict murders, except that the offender has a gang affiliation, which dramatically changes the dynamics of the offense. The gang-motivated cases are often perpetrated by multiple offenders, and have a level of organization that is typical of gang activity. Non-specific motive: hose which cannot be readily classified, usually because of ambiguity as to the offender's motivation – essentially only the offender knows the reason for the murders. Very frequently, the offender has a history of psychological problems or mental illness.
 * Lack of research
 * defined as the killing of three or more people in one place, at one time.
 * Levin and Fox (1996) use a single criterion– motivation – in creating their own typology. most mass murder cases are motivated by vengeance. three subtypes: individual-specific – where the offender targets particular people; category-specific – where particular groups of people are targeted; and, nonspecific – where the murders are precipitated by the offender's paranoia, and where the offender does not have specific targets. Additionally, mass murders may also be classified as occurring out of a warped sense of love – as would be the case with some family massacres, or oriented toward profit – as with felony murder, or result from acts of terrorism.
 * Kelleher's classification system (1997) suffers from some of the same limitations. identified seven groupings: revenge – essentially the same as that found in Levin and Fox, although without the targeting; perverted love – again similar to Levin and Fox's "warped sense of love" category, involving the killing of family or loved ones; politics and hate – ideologically motivated, usually involves acts of terrorism; sexual homicide – typically the motivation in serial murder actually applies to only two cases; mass execution – involves the contract murder of several people in a single incident; the insane – for whom Kelleher can find no other motivation than mental illness; and cases for which he can find no motivation.
 * Classification according to Petee, Padgett and York: eight substantive categories, and an additional grouping which is residual in nature
 * anger/revenge - specific person(s) target: offender seeks revenge against particular people. The targets in this type of an offense are known to the offender, and who were perceived to have wronged the offender in some way. There are precise targets for killing, and the offender will sometimes avoid injuring other innocent bystanders unless they interfere with the offender in some way.
 * anger/revenge – specific place target: targeting of a determinate location for the offense. The site that is targeted for the mass murder usually has some sort of symbolic significance for the offender, and is the focus of the anger. Frequently, the targeted location is connected to an agency or organization that has some authority or control over the offender.
 * domestic/romantic: involves two different types of victims, although the underlying pattern is primarily the same. The domestic cases involve family members in some form of conflict. The typical victimization pattern here is for a husband to kill his wife and children. This represents the most frequent form of mass murder in the United States. Usually this subtype occurs in a household setting, although occasionally they have been known to occur in a public setting. The murders are precipitated by stress or conflict, and is usually cumulative in nature. Other cases in this category involve a situation where an offender has been rebuffed by a romantic interest and retaliates. In fact, this type of mass murder case often involves stalking behavior prior to the actual murder. The offender in these cases often exhibits destructive possessive behavior toward their romantic interest that parallels behavior seen in the domestic cases. This is a type of "fatal attraction" that goes beyond the specific individual and spills over to friends, relatives, or co-workers of the intended victim.
 * Felony related mass murder: killing of three or more people as the result of the commission of another felony – usually robbery. This is an often overlooked category, and represents the most frequent form of mass murder occurring in a public setting. The principal motivation is instrumental, although the murders themselves usually result from either a perceived need to eliminate witnesses, or as a consequence of the offender losing control of the situation.
 * Politically motivated mass murder: involves acts of terrorism. The motivation is primarily ideological, usually for some political cause – although there may be a religious connection – or for political change. The nature of this type of offense is such that typically the offender is absent from the scene of the crime when the victims are actually killed – a sharp contrast to the more intimate involvement in most other mass murder cases.

Kelleher
The definition of when multiple homicides committed in the same incident or episode become categorized as a crime of mass murder has been debated over the years. A common definition of mass murder requires the intentional death of at least four individuals in a single incident. Another interpretation of the term reduces the number of slain victims to three for the crime to be considered mass murder. Both of these definitions are obviously arbitrary and focus exclusively on the number of victims killed. Many mass murderers injure far more victims than they kill; however, they must certainly be considered mass murderers by the obvious intention of their actions. mass murder by intention

Duwe
During the 1980s, journalists, scholars, and other commentators began to assert that the mid-1960s marked the onset of an unprecedented and ever-growing mass murder wave. And the Speck and Whitman massacres were frequently cited as the bellwether of a sharp upward trend in mass murder activity. Results from a recent study have shown, however, that although the mid-1960s marked the beginning of a mass murder wave, it was not unprecedented. Rather, mass murder was nearly as Circle of Distortion 60 common during the 1920s and 30s as it has been since the mid-1960s (Duwe 2004). results revealed that high-profile massacres were significantly more likely to involve large numbers of fatal and wounded victims, stranger victims, public locations, assault weapons, workplace violence, interracial victim-offender relationships and, to a lesser extent, older offenders and gun use. Given that these were the most extreme and atypical mass murders, I argued that the greater coverage given to these massacres was part and parcel of the news media’s attempt to maximize the size of their audience and therefore their profits by catering to the public’s fascination with rare and sensational acts of violence. murder wave during the 1920s and 30s was composed mainly of familicides and felony-related massacres, which, then as now, are among the least newsworthy mass killings The predominance of low-profile massacres during this wave may help explain why mass murder escaped the notice of claimsmakers, not only at that time but also later on in the 1980s when they began making claims about it. Conversely, one of the major reasons why the most recent mass murder wave attracted the attention of claimsmakers was because it contained a significantly greater number of mass public shootings, which, as noted previously, are the most newsworthy mass killings exclusively to the recent rise in high-profile cases, why did claimsmakers start making claims during the mid- 1980s, almost twenty years after the beginning of the increase? The answer to this question lies in the “discovery” of another crime problem—serial murder. Prior to the 1980s, the term ‘mass murder’ was widely used as a catchall phrase to refer to all incidents in which a number of persons were killed. But in the midto late-1960s, there was a dramatic rise in serial killings, or at least in the number publicized by the media The growing prevalence and publicity of serial killings caught the attention of several researchers during the mid-1970s, who coined the phrase ’serial murder’ to describe a string of homicides in which one or more offenders killed a number of persons (at least 3) over a relatively long duration (i.e. days, weeks, months, or even years) with ’cooling off’ periods between the murders The creation of the serial murder concept was notable in that it gave rise to a classification scheme in which ‘multiple murder’, or ‘multicide’, replaced ‘mass murder’ as the umbrella term for homicides involving multiple victims. Under the new typology, multiple murders were distinguished according to the amount of time over which the homicides took place. Whereas serial murders occurred over an extended period of time, mass murders were classified as incidents in which one or more offenders killed a number of victims (at least 3 or 4) over a short period of time (i.e. minutes or hours)Fox and Levin (1994) have attributed the imbalance to the fact that serial murder poses a greater threat to law enforcement, generates more fear and anxiety, and is more sensational. While these are certainly valid points, it is important to emphasize that the media’s initial interest in serial murder during the early 1980s was due, in no small part, to the FBI’s promotion of the problem. During the late-1970s, however, the serial murders committed by the likes of Edmund Kemper, John Wayne Gacy, and Ted Bundy captured a wealth of media coverage. The FBI capitalized on the increased publicity by supplying the media with grossly exaggerated figures on the scale and prevalence of serial killings. murder first began to appear. The creation of the serial murder concept narrowed the meaning of the term mass murder. Although popular use of the new, more limited definition was evident as early as 1984, there was still a tendency, especially early on, to conflate the two types of multiple murder. efforts were made to characterize what kind of problem it was. One of the earliest instances came in a 1984 article that appeared in the New York Times. In discussing the then-recent massacre committed by James Huberty at a McDonald’s restaurant in San Ysidro, California, the article reported that, “mass murderers like Mr. Huberty kill groups of people in a single outburst” on mass murder after the much-publicized massacres committed by James Huberty in 1984 and Patrick Sherrill in 1986, it was not until the late 1980s that the press began devoting serious attention to the “growing” mass murder problem. be white males in their 30s or 40s who have a long history of frustration and failure. They tend to be loners, or people who feel isolated. And they either own guns or are very familiar with them In another article, Levin estimated that in 95 percent of mass murders, there is a precipitating event such as a divorce or job termination also depicted mass murderers as highly suicidal. Table 1 reveals there is not much difference between the typifying examples used by Fox and Levin (“Fox & Levin Examples” column), other academics (“Academic Examples” column), and the news media—namely, journalists (“Media Examples” column). This is because they used many of the same cases to typify mass murder. More important, though, the cases used by claimsmakers were, by far, the most heavily publicized mass killings. prefer to use high-profile mass murders as typifying examples. But as Table 1 shows, the heavily publicized typifying examples used by claimsmakers are hardly representative of mass murder. Indeed, compared to mass killings in general, the 56 cases used as typifying examples were more likely to involve larger body counts, stranger victims, public locations, assault weapon use, workplace violence, interracial victimoffender relationships, older, suicidal offenders, and slightly more likely to involve gun use and white offenders. likely to use felony-related massacres and familicides as typifying examples. insulated in that they receive mostly local coverage.Conversely, only a small minority attract extensive national attention. Claimsmakers have used the cases that garner extensive national attention as typifying examples because these are the cases with which they are the most familiar. instance, mass murder could easily be framed as a domestic violence problem given that familicides are the most common mass killing (Duwe 2000; 2004). Indeed, from 1900-1999, familicides comprised almost half of 909 mass murders that occurred in the United States. The mostly local coverage not only insulates these cases in that they are generally known only on a local basis, but it also inhibits the opportunity for claimsmaking. Around the same time that assault weapons were identified as a new crime problem, a movement began that sought to heighten awareness of workplace violence. By most accounts, 1986 marked the beginning of the rise in workplace violence for that was the year in which Patrick Sherrill, a postal worker, killed 14 and wounded 6 at the post office in Edmond, Oklahoma. In the years following the Sherrill massacre, the workplace mass murders committed by the likes of David Burke, Richard Farley, and Thomas McIlvane (to name a few) received a great deal of publicity, giving claimsmakers opportunities to solidify the perception that workplace violence was a “growing menace” Just as disgruntled employee violence is a rare form of workplace violence, so, too, are workplace massacres a rare form of mass murder. From 1900-1999, these incidents occurred, on average, less than once every two years, accounting for only five percent of 909 mass killings school violence problem. But the incident that came to define the essence of the school violence problem was the now infamous Columbine massacre in Littleton, Colorado in 1999. Garnering international media coverage and intense public interest, the Columbine massacre has served as the landmark narrative for the school violence problem and has prompted fevered debate over the influence of the media—especially violent video games—on the nation’s youth as well as the implementation of “zero tolerance” policies in many schools that have targeted student behavior such as bullying, violent threats, and the possession of firearms and illicit substances. between 1900 and 1996, there were 47 incidents (6%) that involved 65 juveniles as offenders. Not one of the 47 incidents, however, was a mass public shooting, which, prior to 1997, had been committed exclusively by adult males. Instead, juvenile mass murderers are more likely to either kill their parents and siblings in a familicide or to be involved in a felony-related massacre was thus, to a large extent, a historically new phenomenon. But the identification of juvenile mass killers as a new problem is, in several important respects, also a microcosm of mass murder in general. Recall, for example, that even though there was a mass murder wave in the 1920s and 1930s, which was comprised mainly of familicides and felony-related massacres, mass murder was not identified as a new crime problem until the incidence of mass public shootings began to accelerate in the 1960s. Similarly, prior to 1997, juvenile mass murderers were not recognized as a problem because they, for the most part, committed familicides and felony-related massacres, which are the least newsworthy mass murders, i.e. they receive mostly local coverage. But when juveniles began using guns to kill large numbers of innocent victims in public locations—factors that significantly increase the newsworthiness of a mass murder—it was only then that they were identified as a new problem. Even though mass murder rates were relatively high during the 1920s and 1930s, mass murder was not identified as a new crime until the frequency of mass public shootings began to accelerate in the 1960s. Indeed, from 1900-1965, there were only 21 mass public shootings that took place in the United States. From 1966-1999, however, there were 95. The growing incidence of these cases—which are the most newsworthy and, thus, highly visible mass killings—shaped perceptions about the prevalence and patterns of mass murder and helped produce three “spinoff” problems—assault weapons, workplace violence, and school shootings. nationally-publicized mass killings are more familiar to both claimsmakers and the general public, they are the least representative examples of mass murder. Research has shown, for example, that only about one in five mass murderers commit suicide after the homicidal event (Duwe 2000, 2004). Still, the incidence of suicidal behavior among mass killings is at least five times that of ordinary homicides, where the incidence of homicide-suicide is between 1.6 and 4.0 percent. between 1900 and 1999, not one was committed by a female. Instead, the mass murders committed by females tend to be familicides in which they kill their children and, occasionally, their spouse or boyfriend.
 * The Speck and Whitman killings have also played a significant role in shaping what is known about mass murder, which is generally defined as an incident in which a number of victims (at least three or four) are killed within a short period of time (i.e. 24 hours)
 * Recent research likewise suggests that the news media present a distorted image of mass murder
 * The
 * The mass
 * But if the “discovery” of mass murder was due
 * It is within this context that claims about mass
 * After mass murder was identified as a new crime,
 * Although the news media ran a few feature stories
 * mass murderers fit a fairly rigid profile. They tend to
 * A number of claimsmakers
 * These findings indicate that claimsmakers clearly
 * The results further show that claimsmakers were less
 * As noted earlier, the vast majority of mass killings are
 * For
 * Most recently, mass murder has been framed as a
 * Of 828 mass killings that took place
 * The series of school massacres that began in 1997
 * Although the
 * Of the 116 mass public shootings that occurred

Furthermore
In colloquial language the term mass murderer is commonly used to describe anyone who intentionally caused, directly or indirectly, the death of many people. This rather vague definition is applied on states, governments, organziations, groups or persons who order genocides,  massacres,  war crimes,  terrorist acts or similar deeds and their perpetrators, as well as individuals who do not act on behalf of higher institutions, but out of their own personal motivations, like  school shooters,  spree killers,  arsonists and even  serial killers.

The focus of this list, lies on the latter group, individuals, with the restriction to persons who are directly responsible for each death, meaning targeting every single person separately. This excludes arsons, bombings, poisonings or other forms of mass murder where the perpetrator has no direct control on who will fall victim to his crime, but includes terrorist acts by lone gunmen which are later claimed to be perpetrated in the name of an organization, e.g. the Mercaz HaRav massacre. Furthermore serial killers are also left out, because their modus operandi of killing, as well as their motivations are significantly different from common mass murderers and spree killers.

According to the USA Bureau of Justice Statistics mass murder is defined as "the murder of four or more victims at one location, within one event." In regards of this list, this definition is insufficient though, as it does not explain further what can be seen as "one location", e.g. it leaves unclear if a neighbourhood is viewed as one location or as many, counting every house separately. It also does not explain if a whole shooting spree, stretching over hours or maybe days can be seen as one big event, or just as a sequence of smaller events. Further this definition does not include those who did not kill four or more, but set out with the intention to murder as many people as possible, e.g. Denis Lortie who killed three and therefore would not be a mass murderer, according to the above definition, but the 13 people he left injured certainly qualify his rampage as attempted mass murder.

Generally, the deeds of individual mass murderers have in common that the attacks on their victims come in rather short succession without much time to "cool down" and their rampages rarely last longer than a few hours. Also, many of them do not survive their crimes themselves, either because they finish them by committing suicide, or get killed. Only very few get away uncaught.

Besides that, many distinctions can be made within the mass murderer category, though the transition from one group to the other can be smooth. For one there are mass murderers whose crimes are more or less spontaneous, like the case of Carl Brown, often involving alcohol abuse beforehand. On the other hand there are mass murderers who make extensive planning, sometimes months in advance before they put them into practice. Examples for this would be the Columbine massacre or the Virginia Tech massacre. Then there are cases where the victims are very carefully chosen, either because of their relation to the perpetrator or their relation to each other. Those in this group are more likely to take great care to really kill their victims, but also often end up in killing everyone at hand. Typical examples would be family murders, attacks on ethnic or religious groups, or the notorious "hit list". Other mass murderers do not have a certain target and kill people just at random without caring whom they are hitting, often simply moving from one victim to the next, after it was hit. Another distinction would be that some stick to one location, like George Hennard, while others keep moving.

The motivations behind mass murders can be many. From simple robbery, financial and social problems or religious fundamentalism and racism, to outright hatred towards the whole world, the motives cover a broad range, with revenge being maybe the most predominant of them all. Many mass murderers seem to suffer from depression or narcissism and are often stating to have been victims of bullying, mobbing or other forms of humiliation.

For more comprehensive information which cases are included in every subsection, see there.