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BEDFORD, N.Y. (CBS/AP) — The FBI is investigating the discovery of an explosive device at the New York home of billionaire philanthropist George Soros.

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Authorities say the device was found in a mailbox.

A law enforcement official told The Associated Press the device “had the components” of an actual bomb, including explosive powder. Officials say that Soros has been the target of right-wing conspiracy theorists.

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Soros, who is Jewish, has also been the target of anti-Semitic smears. Some have falsely accused him of being a Nazi collaborator during World War II, when he was a child in Hungary.

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Activists frequently post on social media the addresses of his homes, sometimes along with threats.

Authorities are investigating how the package was delivered.

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(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)