The attacker in the Minneapolis school shooting filled hundreds of pages in her diaries, documenting a fascination with school shooters, a desire to kill President Trump, and a toxic mix of racism, antisemitism and Islamophobia.

But in the aftermath of the shooting on Wednesday at Annunciation Catholic Church, many right-wing commentators zeroed in on a single facet of the attacker’s life: At 17, the shooter legally changed her name to Robin Westman from Robert Westman, because she “identified as female and wants her name to reflect that identification,” according to court documents.

The shooting has inflamed an already vitriolic debate over the very legitimacy of transgender identity. Several prominent right-wing activists have pointed to the attacker’s own seeming ambivalence about her gender identity to bolster their contention that all trans people engage in a form of self-deception. Others have gone further, using this case to falsely portray all transgender people as prone to mental illness and violence.

Matt Walsh, a writer and podcaster at The Daily Wire, a right-wing site, posted on social media that “when you affirm the perverse fantasies of sick and delusional people — and you do it systematically, at scale — you are creating precisely this kind of catastrophe. It was inevitable.”

Like other commentators, he referred to the shooting as an act of “trans terrorism.”

The focus on Ms. Westman’s gender identity echoed the politicized reaction to a 2023 mass shooting at the Covenant School in Nashville, which was carried out by a former student whom the police said was transgender. As with that case, Minneapolis authorities have not shared any evidence linking the shooter’s gender identity to the motive for the attack, which killed two children and injured 18 others.