The man who bludgeoned former House Speaker Nancy Pelosi鈥檚 husband with a hammer last year consumed a steady diet of right-wing conspiracy theories before an attack that took place with the midterm elections less than two weeks away.

As the 2024 presidential campaign heats up, experts on extremism fear the threat of politically motivated violence will intensify. From 鈥淧izzagate鈥� to QAnon and to 鈥淪top the Steal,鈥� conspiracy theories that demonized Donald Trump鈥檚 enemies are morphing and spreading as the front-runner for the 2024 Republican nomination aims for a return to the White House.

鈥淣o longer are these conspiracy theories and very divisive and vicious ideologies separated at the fringes,鈥� said Jacob Ware, a research fellow at the Council on Foreign Relations who focuses on domestic terrorism. 鈥淭hey鈥檙e now infiltrating American society on a massive scale.鈥�

A federal jury on Thursday convicted David DePape of attacking Paul Pelosi at his San Francisco home on Oct. 28, 2022. Before the verdict, DePape testified that he had intended to hold Nancy Pelosi hostage and 鈥渂reak her kneecaps鈥� if the Democratic lawmaker lied to him while he questioned her about what he viewed as government corruption. She was in Washington at the time of the assault.

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In online rants before the attack, DePape echoed tenets of QAnon, a pro-Trump conspiracy theory that has been linked to killings and other crimes. A core belief for QAnon adherents is that Trump has tried to expose a Satan-worshipping, child sex trafficking cabal of prominent Democrats and Hollywood elites.

Trump has amplified social media accounts that promote QAnon, which grew from the far-right fringes of the internet to become a fixture of mainstream Republican politics.

Many rioters who stormed the Capitol on Jan. 6, 2021, espoused QAnon鈥檚 apocalyptic beliefs online before traveling to the nation鈥檚 capital for Trump鈥檚 鈥淪top the Steal鈥� rally that day. A message board formerly known as TheDonald.win was buzzing with plans for violence days before the siege.

Before QAnon, many Trump supporters embraced the debunked 鈥淧izzagate鈥� conspiracy theory that prominent Democrats were running a child sex trafficking ring out of a Washington pizzeria鈥檚 (nonexistent) basement. In 2017, a North Carolina man was sentenced to prison for firing a rifle inside the restaurant.

In his 2024 campaign, Trump has ramped up his combative rhetoric with talk of retribution against his enemies. He recently joked about the hammer attack on Paul Pelosi and suggested that retired Gen. Mark Milley, a former Joint Chiefs of Staff chairman, should be executed for treason.

Threats against lawmakers and election officials are rampant, with targets spanning the nation鈥檚 political divide: A California man awaits trial on charges that he plotted to kill Supreme Court Justice Brett Kavanaugh, a Trump nominee, at his Maryland home.

Trump鈥檚 loss to Democrat Joe Biden in the 2020 election did not end the spread of QAnon-influenced conspiracy theories or its unrealized prophecies. The leaderless movement鈥檚 ever-changing ideology often adopts beliefs from other conspiracy theories.

鈥淚t鈥檚 been really good at evolving with the times and current events,鈥� said Sheehan Kane, data collection manager for the University of Maryland-based Consortium for the Study of Terrorism and Responses to Terrorism, or START.

In a 2021 article, Kane and START senior researcher Michael Jensen examined QAnon-inspired crimes committed by 125 adherents since the conspiracy theory originated on the 4chan imageboard in 2017. They found that more 鈥渆xtremist offenders鈥� were connected to QAnon than any other extremist group or movement in the United States.

鈥淚n 2020, millions of people were radicalized on behalf of this conspiracy theory. It鈥檚 really hard to tell who is going to mobilize on behalf of a conspiracy theory,鈥� Kane said.

DePape, the Paul Pelosi attacker, testified that his interest in right-wing conspiracy theories started with GamerGate, an online harassment campaign against feminists in the video game industry. Beginning in 2014, misogynistic gamers terrorized female game developers and other women in the industry with rape and death threats.

Brianna Wu, one of GamerGate鈥檚 original targets, said she wasn鈥檛 surprised to hear it linked to a politically motivated attack nearly a decade later. Wu said GamerGate emerged from the same online recesses that spawned far-right conspiracy theories such as Pizzagate and QAnon.

鈥淭his is a pattern of radicalization that we鈥檙e seeing over and over and over in every single bit of politics,鈥� Wu said. 鈥淭his is not a right-versus-left issue. This is a radicalization issue that is happening online. We need a policy response.鈥�

DePape testified that he went to Nancy Pelosi鈥檚 home with plans to interrogate her about Russian interference in the 2016 election. He said he intended to wear an inflatable unicorn costume while recording it and then upload the video to the internet.

DePape allegedly told authorities that his other targets included a women鈥檚 and queer studies professor at the University of Michigan. He told jurors that he heard about the professor while listening to a conservative commentator.

DePape鈥檚 spiral into conspiracy theories is a textbook tale of radicalization, according to experts on extremism who say that the mainstreaming of false, bigoted and harmful ideas on radio shows, cable news, social media websites and other public online forums has made them far more accessible.

The problem is exacerbated by lax content moderation on social media and a growing 鈥渃onspiracy-creating cottage industry鈥� looking to use extreme rhetoric to cash in or widen their audience, said American University professor Brian Hughes, associate director of the Polarization and Extremism Research and Innovation Lab.

鈥淪ome of the people in that wide audience are going to be people like DePape, who are intentionally going to commit an act of violence based on this false and harmful information that they鈥檝e been served,鈥� Hughes said.

Conspiracy theories are alluring by design, driving some who are susceptible to them to completely immerse themselves, said Amarnath Amarasingam, an extremism researcher and professor at Queen鈥檚 University in Canada. DePape testified that before the attack, he frequently played video games for hours on end while listening to political podcasts.

Repeatedly hearing that the political opponents or government leaders are responsible for evil acts give believers a scapegoat for their troubles and a 鈥渕oral mission鈥� to do something about it, Amarasingam said.

American election years are often characterized by violence, said Ware, of the Council on Foreign Relations, whether it鈥檚 hate crimes in response to a particular candidate鈥檚 identity or violent reactions to unfavorable results. 鈥淪o we should absolutely expect such incidents in 2024,鈥� he said.

Trump鈥檚 return to the ballot next year, as well as his current legal battles, are sure to amplify politicized rhetoric and could drive more extremist violence, experts said.

鈥淒onald Trump has a knack for tacitly endorsing violence without saying anything that鈥檚 really a clear endorsement of it, necessarily,鈥� Hughes said.

To combat potential violence, Americans should try to turn down the temperature of political rhetoric and look out for loved ones who may be spiraling down a path toward radicalization, experts said.

鈥淪pending hours and hours consuming conspiracy theory material is intoxicating,鈥� Hughes said. 鈥淚t anesthetizes you from the worries of your day to day life in the same way that certain drugs do. And I think that we need to reorient our thinking a little bit in that direction, so that we can begin to view this as the public health problem that it really is.鈥�

Ali Swenson And Michael Kunzelman, The Associated Press