On May 27, 2017, 35-year-old Jeremy Christian approached two Muslim women — one of whom wore a hijab — on a light-rail train in Portland, OR, and, according a witness, yelled “Get off the bus and get out of the country because you don’t pay taxes here!” Christian continued to rant and rave until three men, 21-year-old Micah David-Cole Fletcher, 53-year-old Ricky John Best, and 23-year-old Taliesin Myrddin Namkai-Meche, intervened.

In response, Christian attacked the men, stabbing both Best and Namkai-Meche to death — he allegedly slashed their throats — while Fletcher was hospitalized with non-life-threatening injuries. He is now being held without bail on two charges of aggravated murder, two charges of intimidation, one charge of attempted murder, and one charge of being a felon in possession of a restricted weapon.

Upon closer inspection it was discovered that Christian was a complicated figure with a schizophrenic political ideology and an extensive criminal background that includes convictions for first-degree robbery and second-degree kidnapping. Christian apparently holds white supremacist views, and was heard shouting “Fuck all you niggers!” and “Hail Vinland!” at a right-wing March for Free Speech event on April 29th. He was photographed at that same rally brandishing a baseball bat and giving a Nazi salute.

At the same time, Christian’s Facebook posts included statements supporting Bernie Sanders’ presidential campaign, calling for the execution of physicians who circumcise babies, praising far-right terrorist Timothy McVeigh, joking that he wanted to defend the Nazis in a debate against a Nuremberg prosecutor, and claiming that if Trump were Hitler he would be interested in “joining his SS.” There is also debate over whether or not Christian suffers from any mental illnesses.

And while the details of Mr. Christian’s background and the murders will continue to come to light, it appears likely that he’s just the latest killer linked to the racist alt-right movement. In fact, between 2015, when the movement first came to prominence, and the present day, at least four alt-right killers have taken the lives of nearly 20 people.

1. Dylann Roof

On June 17, 2015, 21-year-old Dylann Storm Roof walked into Emanuel African Methodist Episcopal Church — a historically black church in Charleston, South Carolina — and joined a group of parishioners during their Bible study. Roof waited for them to bow their heads in prayer, then pulled a Glock .45 semiautomatic handgun from his fanny pack and opened fire.

When one of the victims, Tywanza Sanders, asked Roof to explain himself, Roof replied, “I have to do this, because you’re raping our women and y’all taking over the world,” before fatally shooting Sanders five times. By the end of his massacre, Roof had killed nine people between the ages of 26 and 87, including senior pastor and SC state senator Clementa C. Pinckney.

On his personal website, The Last Rhodesian, he posted his racist manifesto, according to which Roof had become radicalized online through websites such as the Council of Conservative Citizens. He referred to blacks as “stupid and violent,” praised segregation as a “defensive measure,” and revealed that he chose Charleston as a target because it once “had the highest ratio of blacks to Whites in the country.”

His digital footprint also included posts on Stormfront and The Daily Stormer — gutturally racist and misogynist websites, the latter of which is now the most popular alt-right website on the Internet. And although Daily Stormer founder Andrew Anglin called the murder of nine unarmed churchgoers an “insane act,” the website’s administrator Andrew Auernheimer called Roof’s actions heroic and advocated for the mass murder of blacks — including babies and the elderly.

Roof was charged with 33 counts in his federal indictment and, in December 2016, was found guilty on them all. A month later, a jury sentenced the remorseless killer to death. And while unsealed trial documents revealed Roof to have suffered from mental disorders, including Social Anxiety Disorder and Schizoid Personality Disorder, Roof chose to hide these findings from jurors because he believed it would ruin his reputation among white nationalists.

It was later revealed that Roof professed the deluded belief that his fellow white nationalists would overthrow the U.S. government, free him from death row, and reward him with a high position in the new post-revolution government, such as governor of South Carolina.

2. Alexandre Bissonnette

On January 29, 2017, Alexandre Bissonnette walked into the Quebec Islamic Cultural Center and “fired indiscriminately” at the mosque’s worshipers during their evening prayer. The attack left six dead, including a university professor, and 19 wounded. According to Bissonnette’s acquaintances, the 27-year-old Université Laval student held extreme anti-immigrant and anti-feminist views.

One of the killer’s friends, Vincent Boissoneault, told The Globe and Mail that they often had arguments over Bissonnette’s hatred of refugees and his support for racist, right-wing politicians Marine Le Pen and Donald Trump. “I wrote him off as a xenophobe. I didn’t even think of him as totally racist, but he was enthralled by a borderline racist nationalist movement,” Boissoneault said.

And François Deschamps, who runs a refugee-support Facebook page, recognized Bissonnette’s photo from repeated comments he left. According to Deschamps, Bissonnette “was someone who made frequent extreme comments in social media denigrating refugees and feminism. It wasn’t outright hate, rather part of this new nationalist conservative identity movement that is more intolerant than hateful.”

Bissonnette has, thus far, been charged with six counts of first-degree murder and five counts of attempted murder with a restricted weapon. He has not yet been charged with any terrorism-related offenses, which Canadian legal experts admitted would be unlikely.

Today, Quebec Court Judge Jean-Louis Lemay responded to the prosecution’s request for a three month delay by reminding them that murder suspects must be tried within 30 months, in accordance with a decision made last year by the Supreme Court of Canada.

3. James Jackson

On March 20, 2017, a 66-year-old black man named Timothy Caughman was collecting cans to recycle in Manhattan when he was approached by James Jackson. Little did Caughman know that Jackson, a white, 28-year-old Army veteran, was planning on murdering him as part of a “practice run” before embarking on a killing spree of black men in Time Square.

Jackson plunged a 26-inch sword into Caughman’s chest, puncturing several organs, and fled the scene. He then washed the blood off himself and ditched his blade in a trashcan, but turned himself in after seeing pictures of himself in media reports. As Jackson told Times Square police officers, “You need to arrest me. I have knives in my pocket.”

Following his arrest, Jackson admitted in a jailhouse interview that he harbored an intense hatred of black people, and wanted to murder several in order to deter white women from dating black men. A Maryland native, he chose Times Square in order to maximize the crime’s publicity and terrorize a greater number of people.

Jackson remarked that he had no idea Caughman was elderly, and would rather have murdered a “young thug” or “successful older black man with blonds … people you see in Midtown. These younger guys that put white girls on the wrong path.” He also advised “good white women” to “have as many children as possible.”

And, like Dylann Roof, Jackson was drawn to online hate sites, including The Daily Stormer, which he mentioned as one of the places where he could speak to like-minded people. And on YouTube, Jackson subscribed to a number of white supremacist channels, including RamZPaul, Walt Bismarck, the National Policy Institute, Red Ice TV, Millennial Woes, and Stefan Molyneux.

On March 27, 2017 it was reported that a grand jury had chosen to indict Jackson on charges of murder as an act of terrorism. Manhattan District Attorney Cyrus R. Vance, Jr. summed up the tragedy, stating that Jackson “prowled the streets of New York for three days in search of a black person to assassinate in order to launch a campaign of terrorism,” and acted on his plan by “randomly selecting a beloved New Yorker solely on the basis of his skin color, and stabbing him repeatedly and publicly on a Midtown street corner.”

4. Sean Urbanski

On May 20, 2017, a black 23-year-old college student named Richard Collins III was only days shy of graduation from Bowie State University. A successful participant in the ROTC program, Collins had just been commissioned into the U.S. Army with the rank of second lieutenant — friends say he aspired to be a general. As he waited at the University of Maryland bus stop at 3:00 a.m. Collins and two UMD students were approached by 22-year-old Sean Urbanski.

Urbanski, who was allegedly intoxicated at the time, walked toward Collins and instructed him to “Step left, step left if you know what’s best for you.” Collins calmly replied “No,” and refused to budge. Urbanski then stabbed Collins in the chest with a folding knife and fled. Collins later died at the hospital.

News reports quickly zeroed in on Urbanksi’s online activities. The UMD student was a fan of a now-defunct white supremacist Facebook page called “Alt-Reich: Nation.” UMD Police Chief David Mitchell addressed the connection between Urbanski and the racist Facebook page during a press conference, and called it “despicable.” “It shows extreme bias against women, Latinos, members of the Jewish faith, and especially African Americans,” he said.

Urbanski was charged with first-degree murder, second-degree murder, and first-degree assault and denied bond by Maryland District Judge Patrice E. Lewis, who called him “an absolute danger to the community.” The FBI is currently investigating Collins’ murder as a potential hate crime, and will continue to mine Urbanski’s background and social media history for evidence.