Serial and Mass Murder Exam 2

Definition of mass killing

Four or more victim fatalities; includes all weapons, not only firearms.

Mass killings in the U.S. (2006–2021)

482, averaging about 30 per year.

Mass killings involving firearms

78%; the remaining 22% involved other weapons.

Most common type of mass killing

Family massacres, about 48%.

Public massacres and felony-related killings

About 20% each of mass killings.

Average annual mass public shootings

About six; the range was 3 in 2020 to 10 in 2018.

Mass killings as a share of all homicides

About 1.2% at the 2016–2019 peak.

Most common firearm type in mass killings

Handguns, at 51.6% of weapons used; rifles were less common than assumed.

Mass-killing epidemic theory

The lecture says annual counts were relatively stable since 2006 while public fear rose.

Increase in mass-killing severity (2016–2019)

A small number of unusually lethal events.

Mass public shootings in 2020 and 2021

The count dipped to three in 2020 during COVID and rebounded in 2021.

Public fear of mass shootings

48% of Americans surveyed by Gallup in 2019 worried about becoming a victim.

Avoidance of public places

33% reportedly avoided public places because of mass-shooting concerns.

Misconception about gun deaths

25% mistakenly believed mass shootings cause more gun deaths than suicides or ordinary homicides.

Active-shooter trend data limitation

Older events were identified retrospectively; less serious events were undercounted in earlier news archives.

Active-shooter events without fatalities

12% in 2000–2004 versus 33% in 2016–2020.

Mass-shooting research versus event counts

Scholarship rose dramatically while event counts remained relatively flat.

Pulse Nightclub shooting (2016)

49 people were killed; the lecture describes it as the deadliest attack on the LGBTQ+ community in U.S. history.

Las Vegas music festival shooting (2017)

60 killed and more than 400 injured; the deadliest mass shooting in modern U.S. history in the lecture.

Las Vegas shooter's motive

The motive was never determined.

Sutherland Springs shooting (2017)

The shooter's prior domestic-violence conviction was not reported by the Air Force to the FBI background-check system.

El Paso Walmart shooting (2019)

The shooter targeted Mexican Americans and posted a white-nationalist manifesto.

Probability of another 60+-fatality attack before 2040

Duwe et al. estimated 30%, with a range of 8%–72%.

Mass public shootings with double-digit deaths in the 2010s

16 of 32 in modern U.S. history.

Family annihilator profile

Usually male, often age 30+, typically kills in a private residence, with interpersonal conflict or financial desperation as common factors.

Male family annihilators

89% according to the lecture.

Family-annihilator suicide rate

About 42%.

Region overrepresented in family annihilations

The South: 47% of cases versus 37.4% of the population.

Felony-related mass killings

Incidents often involve young men, home invasions, and crimes linked to drug trafficking; Black and Hispanic offenders were overrepresented in the lecture's data.

Felony-related offenders under 30

64.6%.

Suicide among felony-related offenders

Rare, at about 0.5%.

Public massacre victim counts

The lecture reports averages of 8.16 killed and 16.41 injured per incident.

Public-massacre assailants under 30

51.2%.

Perpetrator suicide in public massacres

36%.

Regions overrepresented in public massacres

The West; California (14.6%) and Washington (6.3%) led.

Happy Land Social Club fire (1990)

87 people died in a fire at a Bronx social club.

Significance of the Happy Land case

Notoriety depends on more than body count; victim demographics, method, and media attention influence public remembrance.

Why Happy Land received less attention than some shootings

The victims were impoverished Hispanic immigrants, fire was used rather than firearms, and the killings occurred in one event.

Mass-murder planning myth

The belief that mass killers simply “snap” without planning.

Active shooters who planned for over a month

62% in Silver et al. (2018).

Active shooters who planned for over six months

18% in Silver et al. (2018).

Mental script

A repeatedly rehearsed plan that can make an offender appear calm during an attack.

Rampages precipitated by work problems

About 50% according to Hempel et al.

Rampages precipitated by personal relationship conflicts

About 25%.

Victim selection in mass killings

Many offenders select particular victims; indiscriminate attacks on strangers are the exception, not the rule.

Patrick Henry Sherrill's target

Supervisors and disliked coworkers in the 1986 Edmond post-office shooting.

Suicide by proxy

The perpetrator views loved ones as extensions of himself and believes killing them will spare them suffering.

Personal revenge

Targeting specific people because of personal grievances.

Categorical revenge

Targeting people because of their group identity or what they represent.

Societal revenge

Hatred of society as a whole expressed through violence.

Least common revenge category

Societal revenge.

Revenge killers' psychology

Often described as “collectors of injustice” who accumulate grievances and seek to punish those they blame.

Age and revenge killings

Revenge killers may be in their 30s or older because grievances can accumulate over years.

Domestic violence and family-involved mass shootings

In 54% of mass shootings involving family members, the family violence itself is domestic violence; a prior record is not required.

Brown's Chicken & Pasta murders (1993)

Seven employees were killed and the safe was emptied; the motive was profit.

Evidence that cracked the Brown's Chicken case

DNA evidence from a partially eaten chicken left at the scene.

Buddhist Temple murders (1991)

The actual motive was robbery of $2,650, rather than the initially suspected hate crime.

Manila casino attack (2017)

Police determined a local man attempted robbery after losing his job; it was not an ISIS-directed terrorist attack.

Mass shooters with formal psychotic diagnoses

About 11%–12.5% in the lecture's data.

Serious mental illness and mass murder

The lecture states that 99.9998% of seriously mentally ill Americans do not commit mass murder in a given year.

Mental illness and mass murder

The lecture cautions that serious mental illness alone is not a reliable explanation; the vast majority of people with mental illness are not violent mass murderers.

XYY syndrome myth

Richard Speck was falsely reported to have an extra Y chromosome; he did not have XYY.

Risk factor contrasted with the XYY myth

The lecture emphasizes maleness rather than an extra Y chromosome.

Five contributing factors in mass murder

Chronic frustration/depression, externalizing blame, social isolation, a precipitating catastrophe, and access to a powerful weapon.

Chronic frustration and depression

Long-term failure and difficulty coping with life's problems, sometimes involving chronic depression but not necessarily psychosis.

Externalizing blame

Blaming others rather than accepting personal responsibility, potentially leading to revenge against scapegoats.

Social isolation as a contributing factor

Lack of emotional support from friends or family can leave a person without help or perspective.

Precipitating catastrophe

A final-straw event such as financial loss, job termination, humiliation, a breakup, or a custody battle.

Access to a powerful weapon

Can increase the extent of an attack; the lecture contrasts selective firearm attacks with indiscriminate attacks involving fire or bombs.

Mental illness versus motive in mass murder

Mental illness alone rarely explains the event; grievances, blame, isolation, triggers, and access also matter.

Matamoros cult killings (1989)

A Mexican ranch investigation uncovered 15 bodies, including University of Texas student Mark Kilroy, connected to Adolfo Constanzo's cult.

Adolfo Constanzo

Known as “El Padrino,” he was a self-described sorcerer who led the Matamoros cult.

Constanzo's beliefs about sacrifice

He claimed sacrifice would provide protection from bullets and prosecution while the group smuggled marijuana.

Sara Maria Aldrete Villareal

A high-achieving college student described as the Matamoros cult's high priestess.

Cult radicalization

Ordinary people may commit extreme acts when group situations promise self-serving goals such as profit, power, or protection.

Constanzo's methods of encouraging obedience

Rituals, chants, economic incentives, animal sacrifice, and claims that survival depended on absolute loyalty.

Jeffrey Don Lundgren

A self-declared prophet who led the Avery family killings in Kirtland, Ohio, in 1989.

Aum Shinrikyo Tokyo subway attack (1995)

The cult's sarin attack killed 12 people and injured about 5,500.

Appeal of dangerous cults

They can offer belonging and support not contingent on achievement, attracting high achievers and professionals as well as vulnerable people.

Groups targeted for cult recruitment

Adolescents experiencing identity crises, adults experiencing midlife crises, and people who are lonely or distressed.

Four stages of cult involvement

Recruitment, initiation, ritual bonding, and radicalization.

Cult recruitment

The group seeks lonely or distressed people and presents itself as a welcoming family.

Cult initiation

Recruits are encouraged to reject traditional values, praised for “seeing the truth,” and isolated from outsiders.

Ritual bonding

Shared rituals strengthen group ties and deepen commitment.

Cult radicalization

Members may be directed toward violence; group identity and fear of rejection can make refusal difficult.

Homicide versus suicide in cult deaths

Powerful leaders may command followers to die, and followers may comply out of loyalty.

Jonestown (1978)

More than 900 followers of Jim Jones died after taking poison or being forcibly injected with cyanide-laced drink.

Heaven's Gate (1997)

Thirty-nine members died believing their souls would ascend to the “Next Level” aboard a spacecraft following the Hale-Bopp comet.

Branch Davidians at Waco

More than 80 followers, including children, died in a fire after a 51-day FBI/ATF standoff in 1993.

Order of the Solar Temple deaths

Members died across Canada and Europe in multiple incidents; some deaths were suicides and others involved drugging or homicide.

Satanism as an explanation for murder

The lecture cautions that killers may use Satanism as an excuse and that violent impulses may predate the ideology.

Richard Ramirez (“The Night Stalker”)

A serial killer who invoked Satanism and left Satanic symbols; the lecture reports 13 murders by August 1985.

David Berkowitz (“Son of Sam”)

A New York shooter who killed six and wounded seven in 1976–1977; a Satanic-cult conspiracy theory was later proposed.

Satanic Panic in the West Memphis Three case

The community believed the murders involved Satanic rituals despite unreliable evidence and later exculpatory DNA evidence.

West Memphis Three convictions

The convictions were questioned because witnesses were unreliable and DNA evidence matched neither the victims nor the defendants.

West Memphis Three release

They were released in August 2011 after about 18 years.

Later medical review in the West Memphis Three case

Some apparent ritual injuries were attributed to animal bite marks rather than ritual knife wounds.

Why sex-motivated serial murders are difficult to link

They are often stranger crimes with no obvious jealousy, revenge, or greed connecting offender and victim.

Murder risk for sex-trade workers

Lowman and Fraser reported that sex workers were 60–120 times more likely to be murdered than females not in the sex trade.

Serial murder cases involving sex-trade workers

The share rose from 13% in the 1970s to 43% in the 2000s, even as overall serial murder declined.