On the morning of 27 August, Robin Westman approached Annunciation Catholic School in Minneapolis armed with a pistol, a shotgun, and a revolver. He opened fire during the first Mass of the new school year, killing two young children and wounding many others before turning one of the guns on himself.

In the wake of such senseless violence, Americans instinctively perform cultural autopsies, looking for explanations. But Westman’s behaviour didn’t lend itself readily to the usual analyses. Hours before the shooting, he uploaded a video in which he can be seen pacing his room in pixelated shadow, flaunting his arsenal. The slogans scrawled in white marker across his guns and ammunition revealed a disturbed mind, addled by dehumanising online memes plucked from trolling subcultures associated with both sides of the political spectrum. “Burn Israel,” “Sponsored by Blackrock,” and “Kill Donald Trump” appeared alongside right-coded catch phrases such as “We Wuz Kangz,” “Nuke India,” and “Kick a spic.” (In a grotesque illustration of horseshoe theory, slogans such as “Extra thicc Jew gas” and “6 million wasn’t enough” could be shoehorned into either category of extremism.) Like the murder of conservative political activist Charlie Kirk, which took place two weeks later, the crime became a Rorschach test for America’s competing cultural projections.

While Westman’s political ideology (insofar as he had one) is unknown, one thing we do know is that the killer was a biologically male 23-year-old who identified as transgender. Robert Westman became “Robin Westman” at the age of seventeen—a fact that many media outlets originally chose not to report. In keeping with the taboo against “deadnaming” trans-identified individuals—even murderers—they posthumously honoured Westman’s “gender identity”; and so gave Americans the false impression that the carnage at Annunciation Catholic School had been committed by a woman.

Westman left a notebook full of rueful references to gender dysphoria, such as ‘I don’t know if I am a trans girl’; ‘my face never matches how I feel’; and ‘I am tired of being trans, I wish I never brainwashed myself.’

While today’s mass shooters are more likely than their predecessors to be radicalised online, they also tend to exhibit many of the same risk factors that have always been associated with this kind of crime—including mental instability and an all-consuming fixation on (often imaginary) grievances. Elliott Rodger, the self-styled “Supreme Gentleman” of incel lore who murdered six and injured fourteen in Isla Vista, California eleven years ago, was enraged by the fact that he wasn’t sexually desirable to women (which, of course, he blamed on society). Westman, by contrast, left a notebook full of rueful references to gender dysphoria, such as “I don’t know if I am a trans girl”; “my face never matches how I feel”; and “I am tired of being trans, I wish I never brainwashed myself.”