The man who shot nine people to death in Dayton, Ohio, seethed at female classmates and threatened them with violence.
The man who massacred 49 people in an Orlando nightclub in 2016 beat his wife while she was pregnant, she told authorities.
The man who killed 26 people in a church in Sutherland Springs, Texas, in 2017 had been convicted of domestic violence. His ex-wife said he once told her that he could bury her body where no one would ever find it.
The motivations of men who commit mass shootings are often muddled, complex or unknown. But one common thread that connects many of them — other than access to powerful firearms — is a history of hating women, assaulting wives, girlfriends and female family members, or sharing misogynistic views online, researchers say.
As the US grapples with the mass shootings in Dayton and El Paso and debates new red-flag laws and tighter background checks, some gun control advocates say the role of misogyny in these attacks should be considered in efforts to prevent them.
The fact that mass shootings are almost exclusively perpetrated by men is "missing from the national conversation," said Governor Gavin Newsom of California. "Why does it have to be, why is it men, dominantly, always?"
While a possible motive for the gunman who killed 22 people in El Paso, Texas, has emerged — he posted a racist manifesto online saying the attack was in response to a "Hispanic invasion of Texas" — the authorities are still trying to determine what drove Connor Betts, 24, to murder nine people in Dayton, including his own sister.
Investigators are looking closely at his history of antagonism and threats toward women, and whether they may have played a role in the attacks.
Since the killings, people who knew Betts described a man who was offbeat and awkward; others recalled his dark rages and obsession with guns.
Those rages were frequently directed at female acquaintances. In high school, Betts made a list threatening violence or sexual violence against its targets, most of whom were girls, classmates have said. His threats were frightening enough that some girls altered their behavior: Try not to attract his attention, but don't antagonise him, either.
"I remember we were all distant, like maybe we should just shy away from him," said Shelby Emmert, 24, a former classmate. "My mom wanted me to just not associate. She said to stay away from Connor Betts."
"An important red flag"
Shannon Watts, the founder of Moms Demand Action for Gun Sense in America, cited a statistic that belies the sense that mass shootings are usually random: In more than half of all mass shootings in the United States from 2009 to 2017, an intimate partner or family member of the perpetrator was among the victims.
(The study, by the gun control advocacy group Everytown for Gun Safety, defined mass shootings as those in which four or more people died, not including the gunman.)
"Most mass shootings are rooted in domestic violence," Watts said. "Most mass shooters have a history of domestic or family violence in their background. It's an important red flag."
Federal law prohibits people convicted of certain domestic violence crimes, and some abusers who are subject to protective orders, from buying or owning guns. But there are many loopholes, and women in relationships who are not married to, do not live with, or have children with their abusers receive no protection. Federal law also does not provide a mechanism for actually removing guns from abusers, and only some states have enacted such procedures.
Judges can consider an individual's history of domestic abuse, for example, under red-flag laws adopted in at least 17 states. Such laws allow courts to issue a special type of protective order under which the police can take guns, temporarily, from people deemed dangerous.
The National Rifle Association, the nation's largest gun lobby, has opposed efforts to expand the situations in which individuals accused of abuse can lose the right to own guns, saying that doing so would deny people due process and punish people for behavior that is not violent.
But Allison Anderman, senior counsel at Giffords Law Center to Prevent Gun Violence, said measures that facilitate the removal of guns from abusers "are a critical step in saving the lives of abuse survivors." And given the link between domestic abuse and mass shootings, she said, these laws may also help prevent massacres.
The plagues of domestic violence and mass shootings in the United States are closely intertwined. The University of Texas tower massacre in 1966, generally considered to be the beginning of the era of modern mass shootings in America, began with the gunman killing his mother and wife the night before.
Devin P. Kelley, who opened fire on parishioners at a Sunday service in Sutherland Springs, on November 5, 2017, had been convicted of domestic violence by an Air Force general court-martial, for repeatedly beating his first wife and breaking the skull of his infant stepson. That conviction should have kept him from buying or owning guns, but the Air Force failed to enter the court-martial into a federal database.
In attacking the church, Kelley appeared to be targeting the family of his second wife.
In a case that highlights the so-called boyfriend loophole, in 2016, a man who had been convicted of stalking a girlfriend and had been arrested on a charge of battery against a household member shot Cheryl Mascareñas, whom he had briefly dated, and her three children, killing the children. Because the man had not been married to or had children with the woman he was convicted of stalking, his conviction did not prevent him from having or purchasing guns.
Inspiration from incels
A professed hatred of women is frequent among suspects in the long history of mass shootings in America.
There was the massacre in 1991, when a man walked into Luby's Cafeteria in Killeen, Texas, and fatally shot 22 people in what at the time was the worst mass shooting in modern US history. The gunman had recently written a letter to his neighbours calling women in the area "vipers," and eyewitnesses said he had passed over men in the cafeteria to shoot women at point blank range.
"Even some of the incidents that people don't know about or aren't really familiar with now or don't come to mind, there definitely is a thread of this anger, and misogyny," said James M. Silver, a professor of criminal justice at Worcester State University who has worked with the FBI to study the motivations of mass gunmen.
In recent years, a number of these men have identified as so-called incels, short for involuntary celibates, an online subculture of men who express rage at women for denying them sex and who frequently fantasise about violence and celebrate mass shooters in their online discussion groups.
Special reverence is reserved on these websites for Elliot O. Rodger, who killed six people in 2014 in Isla Vista, California, a day after posting a video titled "Elliot Rodger's Retribution." In it, he describes himself as being tortured by sexual deprivation and promises to punish women for rejecting him. Men on these sites often refer to him by his initials and joke about "going ER" — or a murderous rampage against "normies," or non-incels.
Several mass killers have cited Rodger as an inspiration.
Alek Minassian, who drove a van onto a sidewalk in Toronto in 2018, killing 10 people, had posted a message on Facebook minutes before the attack praising Rodger. "The Incel rebellion has already begun!" he wrote. "All hail Supreme Gentleman Elliot Rodger!"
And Scott P. Beierle, who last year shot two women to death in a yoga studio in Tallahassee, Florida, had also expressed sympathy with Rodger in online videos in which he railed against women and minorities and told stories of romantic rejection. Beierle had twice been charged with battery after women accused him of groping them.
Federal law enforcement officials said the FBI was looking at whether the gunman in Dayton had connections with incel groups, and considered incels a threat.
Experts say the same patterns that lead to the radicalisation of white supremacists and other terrorists can apply to misogynists who turn to mass violence: a lonely, troubled individual who finds a community of like-minded individuals online, and an outlet for their anger.
"They're angry and they're suicidal and they've had traumatic childhoods and these hard lives, and they get to a point and they find something or someone to blame," said Jillian Peterson, a psychologist and a founder of the Violence Project, a research organization that studies mass shootings. "For some people, that is women, and we are seeing that kind of take off."
David Futrelle, a journalist who for years has tracked incel websites and other misogynistic online subcultures on a blog called "We Hunted the Mammoth," described incel websites as a kind of echo chamber of despair, where anyone who says anything remotely hopeful quickly gets ostracised.
"You get a bunch of these guys who are just very angry and bitter, and feel helpless and in some cases suicidal, and that's just absolutely a combination that's going to produce more shooters in the future," Futrelle said.
Psychiatrists, however, say that the attention on mental health generated by mass shootings, and the common argument that mental illness is the explanation for these massacres, cannot explain the link between misogyny and mass shootings. Misogyny — or other types of hatred — is not necessarily a diagnosable mental illness.
Instead, said Amy Barnhorst, the vice chair of community psychiatry at the University of California, Davis, who has studied mass shootings, what ties together many of the perpetrators is "this entitlement, this envy of others, this feeling that they deserve something that the world is not giving them. And they are angry at others that they see are getting it."
Written by: Julie Bosman, Kate Taylor and Tim Arango
Photographs by: Maddie McGarvey
© 2019 THE NEW YORK TIMES