BERLIN - He mixed extreme paranoia about secret state surveillance with far-right conspiracy tropes, misogyny and racist vitriol.

The gunman who killed nine people in the Frankfurt suburb of Hanau left behind a 24-page rambling screed calling for the “complete extermination” of races he considered inferior; a video blending far-right diatribes, delusional musings and an infamous quote by Adolf Hitler; and an English-language video statement that echoes themes of child sacrifices and disdain for mainstream media found in the QAnon conspiracy theory.

The attacker was found dead at home along with his mother, who may have been his 10th victim. His website and YouTube channel came down almost immediately, as German authorities tried to prevent his rant from spreading across the internet and morphing into an extremist rallying cry, as happened after the mosque killings in Christchurch, New Zealand, last March.

All of the people he killed during his rampage across the city were of foreign origin.

Identified as Tobias Rathjen, the gunman made no direct references to QAnon, far-right memes or other deadly attacks and their notorious perpetrators such as the killer in Christchurch or the gunman in the German city of Halle who killed two people outside a synagogue on Yom Kippur in October.

Germany's federal prosecutor, Peter Frank, described the rant as stocked with “confused ideas and far-fetched conspiracy theories.” It was last modified on Jan. 22 and offered no indication he was planning an attack, according to Rita Katz of the SITE Intelligence Group. The English-language video was completed on Feb. 13, she said.

Despite his incoherence, the 43-year-old tapped into an increasingly widespread vein of conspiracy theories originating in the United States, including many by QAnon, and woven into other specifically German themes.

QAnon, a right-wing conspiracy theory that President Donald Trump is fighting “deep state” enemies and a child sex trafficking ring, seeped into online chatter associated with the far-right Alternative for Germany party beginning in 2018 but remained on the margins, according to a study last year by the Institute for Strategic Dialogue think-tank .

One of the documents posted to Rathjen's website detailed his conviction that he had been under government surveillance since childhood. He blamed the surveillance for his inability to have a relationship with a woman. He also called for wiping out half the world’s population.

He wrote: “The following people must be completely exterminated: Morocco, Algeria, Tunisia, Libya, Egypt, Israel, Syria, Jordan, Lebanon, the complete Arabian Peninsula, Turkey, Iraq, Iran, Kazakhstan, Turkmenistan, Uzbekistan, India, Pakistan, Afghanistan, Bangladesh, Vietnam, Laos, Cambodia and the Philippines.”

In the English-language video, he warned Americans that they are under the control of “invisible secret societies,” and he spoke of subterranean military bases where “they abuse, torture and kill little children.”

Peter Neumann, a senior fellow at the International Centre for the Study of Radicalisation at King’s College London, described the screed as a “do-it-yourself set of beliefs” that is increasingly common among violent far-right extremists. The centre also analyzed a nine-minute video that ended with a twist on a notorious Hitler quote: “I don't believe that the people who are laughing today will be laughing in the future."

“There’s a far-right extremist bent to it. There’s also misogynism. There’s of course evidence of his obsessions, conspiracy theories,” Neumann said.

An FBI bulletin warned last May about the potential for violence among American fringe political conspiracy theorists. Thursday’s rampage may be a new sign that the danger has spread beyond U.S. borders.

Travis View, a conspiracy theory researcher, said that while the gunman’s online ramblings suggest he was influenced by a hodgepodge of paranoid conspiracy theories, including QAnon, some of the beliefs expressed by the gunman diverge from QAnon dogma, such as a passage in which he suggests he was responsible for Trump’s policies and even political slogans.

“That’s very not ‘Q.’ They think that Trump is this super-genius. They would never be so arrogant to suppose that they could give Trump — God emperor — ideas,” said View, who co-hosts The QAnon Anonymous Podcast and has written about QAnon for The Washington Post under his pseudonym. He works as a marketer for a San Diego company and says he uses the pseudonym to protect himself.

View also said the gunman’s delusions about being under surveillance resemble the beliefs of those who call themselves “Targeted Individuals” and are convinced that government agents whom they call “gangstalkers” are using mind-control devices to monitor and torture them .

The gunman’s frustration with women is a common trait among "incels," short for those who are "involuntary celibate." The movement, an online subculture linked to deadly attacks in California, Toronto and Florida, promotes the misogynistic idea that men are entitled to have sex with women.

“There’s a serious question of whether the mental issues were so severe that we can no longer speak of an act of terrorism. It’s not a frivolous question,” Neumann said.

The Confederation of Kurdish Communities in Germany blamed the political climate in Germany, where a prominent member of the Alternative for Germany party suggested that "well-tempered cruelty" is necessary to drive immigrants out of the country.

"Those in positions of political responsibility in this country didn't stand up decisively to right-wing networks and right-wing terrorism," the Kurdish group said. Several of the victims are believed to be of Kurdish origin.

Investigators are looking into the German attacker’s mental state and whether he had accomplices.

"Such a crime doesn't come out of nowhere," said Christine Lambrecht, Germany's justice minister. "It results from hatred in the country that we urgently need to break through."

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Hinnant reported from Paris. Jordans reported from Berlin. Associated Press reporter Michael Kunzelman contributed from College Park, Maryland.

News from © The Associated Press, 2020