By Nate Raymond

NEW YORK (Reuters) - An upstate New York man, who was set to face trial in May for attempting to defraud Facebook Inc and founder Mark Zuckerberg, is missing, his lawyer said on Monday.

Paul Ceglia, 41, had been required to wear an electronic bracelet before his trial. But Robert Fogg, his lawyer, said Ceglia's ankle bracelet was found at his home after the U.S. Marshals Service was dispatched to check on him on Sunday.

Fogg said he has not heard from Ceglia. U.S. District Judge Vernon Broderick has scheduled a hearing for Tuesday that was "most definitely spawned by the recent event," Fogg said.

Representatives for Bharara's office and the Marshals Service did not respond to requests for comment.

Ceglia, of Wellsville, New York, was first charged in 2012. He claimed he was entitled to ownership of half of Facebook, based on a 2003 contract the two had signed, but prosecutors accused him of forging the contract with Zuckerberg, who would be expected to testify at trial.

Ceglia, who was to face trial May 4, has pleaded not guilty. Fogg said Monday that Ceglia has "always been concerned with justice."

"He has always been concerned about if he'd get a fair trial," Fogg said.

The charges flowed from a 2010 civil lawsuit Ceglia filed against Zuckerberg and Facebook in Buffalo, New York.

The lawsuit contended the two men signed a contract when Zuckerberg was a freshman at Harvard University that gave Ceglia half of a planned social networking website.

Zuckerberg had previously done some programming work for Ceglia's company,, and Facebook has said the only valid contract between them related to that company.

Prosecutors said Ceglia forged documents as part of the Buffalo litigation, including the contract and email correspondence with Zuckerberg.

Last year, a Buffalo federal judge dismissed Ceglia's lawsuit, finding the purported contract for an ownership stake in Facebook was doctored. Ceglia is appealing.

The case is U.S. v. Ceglia, U.S. District Court, Southern District of New York, No. 12-cr-00876.

(Reporting by Nate Raymond in New York; Editing by Ken Wills)