Opinion | The Demented Detectives on Seth Rich’s Case (Published 2017)

Seth Rich died on the night of July 10, 2016. The conspiracy theories were born days later. The process by which these baseless theories about his death snaked from Reddit to Twitter to Fox News illustrates just how thin the membrane has become between the conspiracy world and the mainstream.

Police say that Mr. Rich, a 27-year-old on the staff of the Democratic National Committee, most likely died in a botched robbery. But by July 13, alternate explanations emerged: A site called WhatDoesItMean.com claimed he was on his way to the F.B.I. to testify against Hillary Clinton.

Conspiracy theories help people who feel politically disempowered respond to a perceived loss of control. So it made sense, when Mrs. Clinton’s win seemed assured, that supporters of both Donald Trump and Bernie Sanders were convinced that Mr. Rich’s death showed ruthless corruption in the Democratic Party.

Conspiracy theories have been widespread among Americans for years, but they found particular prominence in the 2016 election because many people felt locked out of the process and distrustful of the news media. Mr. Trump, who repeatedly said that the press was dishonest and that the election would be “rigged” against him, fed and fed off this attitude.

But the Rich theories wouldn’t have gone beyond WhatDoesItMean.com and Reddit without the help of prominent backers. In August, Julian Assange insinuated that Mr. Rich could have been the source of the D.N.C. emails put out by WikiLeaks and offered a $20,000 reward for information on Mr. Rich’s death, despite the fact that a hacking persona going by Guccifer 2.0 claimed responsibility. Mr. Assange says that WikiLeaks doesn’t reveal its sources, but if Mr. Rich leaked the emails, he would be able to distance himself from accusations that he’d acted as a funnel for a Russian intelligence operation.

This is how the modern conspiracy ecosystem works. Theories are hijacked by the self-interested. Mr. Assange was trying to protect his reputation. For others, the motive is financial. Alex Jones, the founder of Infowars, claims fluoride is put in the water supply to control people — and then sells a Fluoride Shield supplement. Often the motives are partisan: Both Pizzagate and Spirit Cooking — wild theories that accused Democratic insiders of engaging in satanic rituals and child sex abuse — were shared by right-wing outlets like Drudge Report and The Washington Times to discredit Democrats.

Mr. Assange’s insinuations broke a dam: Before long, private “investigators” emerged, offering their dubious help to the Rich family. A Republican lobbyist named Jack Burkman offered more reward money, walking through Washington neighborhoods with posters reading, “Do you know who murdered Seth Rich?”

That pattern of attention-seekers attaching themselves to the case repeated itself again and again. Robbin Young, a former Playboy model who’s claimed to be in contact with Guccifer 2.0, has implied that she fears being killed as a result of her own “investigating.” Mike Cernovich, a far-right blogger, has also gotten involved. Even the Russian embassy in London tweeted “#WikiLeaks informer Seth Rich murdered in US but MSM was so busy accusing Russian hackers to take notice.”

The biggest fish in this foul pond, though, is Sean Hannity of Fox News, who recently latched onto the Rich story, promoting it on his popular prime-time show and on social media. Mr. Hannity, a fierce Trump partisan, seemed aware that his speculation about Mr. Rich’s death could deflect attention away from the multitude of disasters dogging the White House and at his own scandal-plagued network. And he surely knew that the story would play well with his audience, which was eager to see the news about the Trump team’s Russia connections as a mainstream media smoke screen and Mr. Rich’s murder as the real fire.

After vigorous public shaming — including a Washington Post op-ed essay by Mr. Rich’s parents — and pressure from his show’s advertisers, Mr. Hannity announced that he would stop discussing the murder (“for now,” he added). Fox even retracted a story from its website. He’s still tweeting, though, pledging that he’s close to finding “the truth.”

But the theories aren’t going away. Mr. Rich’s death has now become lodged firmly in the conspiracy firmament. Infowars proclaimed that Mr. Rich was a victim of the “deep state,” using his death as proof that the swamp is so murky that even Mr. Trump can’t drain it. And devotees of Pizzagate have written that they believe that the resolution of the Rich case will help explain a grand unified theory of diabolical government misdeeds. The demented detectives won’t stop.

The ceaseless churn of increasingly unhinged theories — and Fox News’s willingness to put them on air — torments the Rich family. “It is a travesty that you would prompt false conspiracy theories and other people’s agendas,” Aaron Rich, Seth’s brother, wrote in a letter to Mr. Hannity’s producers, “rather than work with the family to learn the truth.”