The teenage gunmen behind Monday’s deadly attack at the Islamic Center of San Diego appear to have left a hate-soaked manifesto praising Adolf Hitler and a string of notorious mass killers, according to law enforcement sources and a report from The California Post.
Authorities are investigating whether 17-year-old Cain Clark and 19-year-old Caleb Vasquez authored the 75-page document before the shooting that left three people dead and ended with both suspects killing themselves, sources said.
The document, investigators believe, lays out an “accelerationist” fantasy of chaos, with the authors allegedly pushing for a race war and the collapse of society. It also includes a scattershot ideological brew that targets virtually everyone: anti-Trump, anti-liberal, antisemitic, homophobic and misogynistic rhetoric, tied together by grievance and nihilism, according to the report.
Sources told the outlet investigators have a copy of the purported manifesto and believe it to be authentic.
According to the report, the manifesto is loaded with Nazi-associated iconography, including the Black Sun, which is associated with Nazi SS head Heinrich Himmler, and Atomwaffen, which is tied to a violent neo-Nazi group. Investigators also reviewed online profiles linked to Clark that featured Nazi slogans, and images of Hitler and German soldiers in World War II formation, the report said.
In one section believed to have been written by Clark, the author claims he is neither left nor right and expresses contempt for both sides, according to the report.
The document also allegedly names multiple ideologically driven killers as inspiration, including Ted Kaczynski, Timothy McVeigh and Norwegian terrorist Anders Breivik.
17-year-old Cain Clark and 19-year-old Caleb Vasquez
Authorities are also scrutinizing references to the 2019 Christchurch mosque shooter, Brenton Tarrant, who the suspects allegedly idolized. The report said the authors named their manifesto after Tarrant and described him as “Saint Terrant,” framing his livestreamed attack as a blueprint.
Jennifer Du, who lives across the street from Clark’s home, said she saw the 17-year-old the day before the attack.
“It’s been unreal. I saw him literally the day before. He just stood there,” Du, 30, told The California Post.
“I didn’t know if he was watching me or something, but he just got food delivery and went back in.”
A next-door neighbor, identified only as Marne, said the family appeared normal and recalled seeing the teen in martial arts gear.
“As far as we knew he was very nice. They were a nice family,” said Marne, 85, who declined to provide her last name.
“We were just flabbergasted,” she added of learning about the attack. “We thought, ‘Oh my god,’ we couldn’t believe it. Just flabbergasted.”
The San Diego Mosque Assassins: The 75 Page Manifesto!
The shooters were not “right or left” politically.
They were Nazi Bolsheviks who blamed “capitalism” and “Trump” for our “joke” of a “democracy” and wanted to burn down the system. pic.twitter.com/7IIQR92VYq
— Andrea Shaffer, Anti-Marxist Warrior (@Andreafreedom76) May 20, 2026
Clark and Vazquez killed three people, including mosque security guard Amin Abdullah, a father of eight whom police say helped slow the attackers and prevented them from reaching schoolchildren nearby. Two other victims were identified as Nader Awad and Mansoor Kazziha.
Investigators are also examining evidence tied to the suspects’ final moments. The report said the livestream appeared to show Clark shoot Vazquez twice in the head before turning the gun on himself.
A law enforcement source previously told media that at least one suspect took a weapon from a parent’s home and left a suicide note referencing racial pride. Authorities and the FBI are continuing to investigate the massacre and are expected to execute additional search warrants, a source familiar with the case said.
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