The American billionaire hedge fund manager and art collector J. Tomilson Hill is the mysterious buyer of an early 17th-century canvas billed as a rediscovered masterpiece by Caravaggio, according to a person with knowledge of the sale.

The painting, “Judith and Holofernes,” depicts a scene from the Old Testament’s Book of Judith in which a Jewish widow saves her besieged city by tempting and then beheading an Assyrian general.

The unsigned artwork was estimated to sell on Thursday in Toulouse, France, for at least $110 million, the highest auction price ever achieved for any artwork in Europe. But on Tuesday, the auctioneers Marc Labarbe and Eric Turquin announced that the painting had sold to a collector outside France and that the auction had been canceled.

That collector is Mr. Hill, who recently retired as a vice chairman of the private equity firm Blackstone and who has amassed a noteworthy collection of Modern and contemporary art as well as old masters. Mr. Hill serves on the board of the Metropolitan Museum of Art and in February opened his own private museum, the Hill Art Foundation, in Chelsea. The Foundation’s first show featured the contemporary artist Christopher Wool (Mr. Hill owns 14 of his paintings). Mr. Hill was unavailable for comment.