Their deaths were at once famous and obscure. Their killers were known, well-liked and walked free. One slaying led to the rise of the Ku Klux Klan. The next, the Anti-Defamation League.

Leo Frank, a Jewish factory superintendent, was convicted of a crime he didn’t commit, then abducted from prison and lynched by a mob. (Anti-Defamation League)

The twin murders of Mary Phagan and Leo Max Frank will always haunt the South, cultural historians say. Phagan, a 13-year-old child laborer at an Atlanta pencil factory, was found strangled in the facility’s basement in 1913. Frank, the factory superintendent and a member of a prominent Jewish family, was convicted of the crime, then kidnapped from prison and lynched in 1915.

Overwhelming evidence implicates Jim Conley, a black factory aide, in Phagan’s murder. Instead, he was the prosecution’s star witness against Frank. A showman under oath, an all white jury relied on his testimony to convict a Jewish industrialist.

Conley was convicted as an accessory after the fact. He spent the rest of his life in and out of prison, mostly on convictions for violence against women.

Today, the murders continue to reverberate in the era of fake news and the alt-right white nationalist movement.

“The Leo Frank case is interesting in that you’re never going to meet a Nazi who doesn’t know about it,” said Heidi Beirich, director of the Intelligence Project at the Southern Poverty Law Center.

After Georgia Gov. John Slaton commuted Frank’s death sentence in 1915 for a dearth of evidence, a mob of Atlanta’s social elites — the self-declared “Knights of Mary Phagan” — abducted Frank from prison.

The operation was well planned. Machinists cut the prison’s phone lines. Others drained the gas out of police cars so they couldn’t give chase. They posted lookouts in the towns along their 150-mile drive to Marietta from the jail in Milledgeville.

They hanged Frank at dawn in an oak grove owned by Marietta’s former sheriff, pointing him toward Phagan’s house.

Local prosecutors vowed they’d track down the lynchers. None ever stood trial.

A month later, a crowd of 30 men, including some of the lynchers, convened on Stone Mountain to christen the revival of the Ku Klux Klan.

More than 100 years later, the effort to implicate Frank in the crime continues. The largest and most easily accessible online databases about the case are run by avowed white supremacists Kevin Strom, a convicted pedophile, and John De Nugent, who claims warring species of ancient aliens colonized the planet, according to the Southern Poverty Law Center.

They maintain leofrank.info, a site branded as “The Leo Frank Case Research Library,” and maryphagan.org.

The Forward, a national Jewish newspaper, investigated Strom and De Nugent’s links to the sites in 2013.

The Web pages, updated sometimes daily, contain thousands of authentic documents about the Phagan murder, including full evidence briefings from the Georgia Supreme Court and photocopies of newspaper articles.

But the sites, of course, dispute the historical consensus of Frank’s innocence. They include links to white supremacist publications National Vanguard, Occidental Dissent and American Mercury. It links to a photo album that includes fabricated images of Phagan. A page titled “Jewish Reaction to the Guilt of Leo Frank” sends readers to the website “The White Network,” which bills itself as a forum for “Whites talking to Whites about White interests.”

Why does the Frank case continue to galvanize the white supremacist community? For one thing, the trial gave rise to the Anti-Defamation League, linking southern black and northern Jewish communities in a cause for civil rights.

“It’s not the case itself so much but how successfully Jews and Jewish interests organized around it that confirms to white supremacists that all the conspiracies about Jewish control of the media are true,” said Jeffrey Melnick, a professor of American studies at the University of Massachusetts at Boston and author of “Black-Jewish Relations on Trial: Leo Frank and Jim Conley in the New South.”

New York Times owner Adolph Ochs mobilized his newsroom to cover Frank’s trial and crusade on his behalf. Advertising magnate Albert Lasker organized Jews from New York, Chicago, Washington and New Orleans to donate to Frank’s defense and publish articles in his favor, said Steve Oney, author of “And the Dead Shall Rise,” considered the definitive work on the Phagan-Frank case.

The strategy backfired. The Jeffersonian, a popular tabloid, began publishing rebuttals to Ochs’s columns and relied increasingly on anti-Semitic tropes to defend Georgia’s reputation.

“When are the Northern Jews Going to Let Up On Their Insane Attempt to Bulldoze The State of Georgia?” read one headline. “WOMANHOOD MUST BE, AND SHALL BE PROTECTED; and we mean to have that understood by lascivious young Jews,” the story concluded.

Another retold accounts of Jewish blood libel, myths of Jews using the blood of gentile children in sacrifice rituals, in medieval Russian villages.

The trumped-up anti-Semitism led to the lynch party’s formation, Oney said, and the slow withdrawal of Jews from southern life. These Web pages try to do the same thing to stoke fears and stereotypes of Jews from a century-old crime, Oney said.

“It’s something I don’t think the Jewish community takes seriously enough,” he said. “The scary thing about it to me is that it portrays itself as a fair and straightforward account of the Frank case.”

It’s old news. And still fake.