One of Donald Trump's aides has lost his job after fanning a conspiracy theory that climaxed at the weekend in gunfire at a pizzeria.
Michael Flynn, 33, left the US president-elect's transition team on Tuesday following his tweets about the so-called Pizzagate fake news story.
His father, Michael Flynn Snr, Mr Trump's pick to be US national security adviser, has also shared viral hoaxes.
The Pizzagate claims led to a gunman firing shots in a restaurant on Sunday.
No one was injured in the incident at Comet Ping Pong in Washington DC.
The suspect told police he had turned up to "self-investigate" online rumour-mongering that the pizzeria was the nexus of a paedophile ring involving Hillary Clinton and one of her aides, John Podesta.
The bizarre and unfounded theory had been spread online by right-wing blogs.
The allegations were also circulated by Mr Flynn Jr, who tweeted after Sunday's gunfire that Pizzagate would remain a story until "proven to be false".
The New York Times reports that he was fired from the Trump transition team on Tuesday but, according to CBS News, he resigned before he was sacked.
The Trump team confirmed the departure of Mr Flynn - who had reportedly been given a .gov email address - but did not confirm it was related to the tweets.
Vice President-elect Mike Pence acknowledged that Mr Flynn Jnr had been helping his father with scheduling and administrative items during the transition but said "that's no longer the case".
Asked repeatedly whether a security clearance was requested, Mr Pence refused to answer directly.
Mr Flynn Snr, 57, has also tweeted out outlandish conspiracy theories accusing Mrs Clinton and her aides of child-sex trafficking.
Among the retired lieutenant general's other tweets was an allegation that President Barack Obama was a "jihadi" who "laundered" money for terrorists.
Critics have said Mr Flynn Snr is unfit to advise the incoming president on the veracity of national security threats facing the US.
In Sunday's armed confrontation, the suspect allegedly walked into Comet Ping Pong and pointed a rifle at an employee before firing shots into the ground.
Edgar Maddison Welch, 28, from North Carolina, has been charged with assault with a dangerous weapon.
The Pizzagate theory originated on alternative message board 4chan, based on emails hacked from the Democratic Party and leaked by Wikileaks.
The restaurant's owner, James Alefantis, a Democratic Party donor, appears in the emails in relation to organising a Democratic fundraiser.
Users of 4chan and another message board, Reddit, had said words in the emails such as cheese, hot dog, and pizza were code for young children and sex acts.