A bomb was discovered Monday in a mailbox at the upstate, New York home of billionaire philanthropist and political donor George Soros. Soros, who is Jewish, is a fixture in far-right and anti-Semitic conspiracy theories circulating in the U.S. and Europe that have been amplified by some mainstream conservative figures.

The explosive device was discovered by one of Soros’ employees at his home in the town of Bedford in New York’s northern Westchester County. According to a statement from Bedford police: “An employee of the residence opened the package, revealing what appeared to be an explosive device … The employee placed the package in a wooded area, and called the Bedford police.” Explosive ordnance technicians from the police bomb squad “proactively detonated” the package, according to a law enforcement official. 

The Hungarian born Soros, now 88 years old, survived the Nazi occupation of Hungary and emigrated to England in 1947 where he studied at the London School of Economics. Later, Soros moved to the U.S. and made his fortune running a hedge fund.

In 1993, Soros established the liberal Open Society Foundations as a clearinghouse for his “democracy promotion” and political activism. The organization, to which he has given at least $18 billion, states that its goal is “to build vibrant and tolerant societies whose governments are accountable and open to the participation of all people.” Soros has also supported the candidacies of Democrats running for office in the U.S.. He has contributed to the campaigns of presidential candidates, John Kerry, Barack Obama, and Hillary Clinton.

In both Europe and the U.S., Soros’ contributions to political causes—which are often perfectly controversial for non-anti-Semitic reasons—have made him a target of populist enmities, accused of pushing a “globalist agenda” to undermine national sovereignty, and a boogeyman of the anti-Jewish and far-right fever swamps. Despite this, right-wing political parties in Israel have at times endorsed the attacks on Soros due to his support for the Obama administration’s Iran deal, and left-wing anti-occupation groups—as detailed last year by Tablet contributor Jamie Kirchick in his article, “Likud Puts Kosher Stamp on Anti-Semitic Attacks Against George Soros.”

Soros, who has been accused of collaborating with the Nazis by well-known figures including Roseanne Barr and Glenn Beck, is now frequently portrayed in terms of classic anti-Semitic caricature—the Jewish puppet master pulling strings in the shadows of world affairs.

The investigation into who placed the bomb at his house is being handled by the FBI.