Weekly fact check: Trump's long history with conspiracy theories, and Biden's misleading union endorsement claim

With just a few weeks to go before Election Day and both presidential campaigns turning up the heat, fact-checking is more important than ever. Here's some of the latest:

During his Oct. 15 town hall, President Trump defended retweeting a conspiracy theory that accused Joe Biden of murder. "The theory, which has no basis in fact, specifically claimed Biden had members of SEAL Team 6 killed to cover up a purportedly failed assassination of Osama bin Laden in 2011. Trump retweeted a post spreading the theory, therefore amplifying the message to his 87 million followers," Angela Fichera and Saranac Hale Spencer report for FactCheck.org. "At the same event, Trump also declined to condemn QAnon — the widespread conspiracy theory movement that baselessly suggests Trump is dismantling an elite child sex trafficking ring involving high-profile Democrats. He claimed he knows 'nothing about' it.

"During a campaign rally, President Donald Trump said that once he came down with covid-19, people for partisan reasons shifted from saying immunity was lifelong to saying it lasted only a few months," Jessica McDonald reports for FactCheck. "Experts, however, haven’t changed their estimates for immunity duration, which remains unknown — but unlikely to be lifelong."

Meanwhile, during Biden's Oct. 15 town hall, Biden said the International Brotherhood of Boilermakers had endorsed him. But that's misleading, Jessica Calefati reports for PolitiFact. The Pittsburgh-area local did endorse Biden, but the organization as a whole, which represents 50,000 industry workers nationwide, did not.

Also during that town hall, Biden insinuated that Republicans eliminated funding for a community policing program. But that's false, Lou Jacobson reports for Politfact. Funding for the Community Oriented Policing Services program, which Biden spearheaded as part of a 1994 crime bill, was not eliminated. "Biden’s campaign told PolitiFact that he was referring to Trump’s fiscal 2019 budget proposal, which would have halved funding for the community policing program. But this proposal wasn’t enacted, and it did not amount to an 'elimination,'" Jacobson reports. "The program is smaller than it was in its early years, when its budget ranged between $1.2 billion and $1.6 billion, and crime rates were higher. But funding was never zeroed out."