The government will call Mark Zuckerberg to testify against an upstate New York man accused of trying to cheat the billionaire founder of Facebook Inc (FB.O) out of half his stake in the social media company, a federal prosecutor said on Tuesday.

Zuckerberg is expected to be a key witness against Paul Ceglia, who is charged with forging a 2003 contract with Zuckerberg that purportedly entitled him to half of Facebook.

“It's a witness that the government 100 percent knows it will be calling at trial,” Assistant U.S. Attorney Christopher Frey said at a court hearing before U.S. District Judge Andrew Carter in New York federal court.

The trial is scheduled for Nov. 17.

The charges stem in part from a 2010 civil lawsuit Ceglia filed against Zuckerberg and Facebook in Buffalo, New York, claiming 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 programing work for Ceglia’s company, StreetFax.com, and Facebook has said the only valid contract between them related to that company.

Prosecutors in Manhattan charged Ceglia in 2012 with forging documents as part of the Buffalo litigation, including the contract and email correspondence with Zuckerberg.

In March, a Buffalo federal judge dismissed Ceglia's lawsuit, finding the purported contract for an ownership stake in Facebook was doctored.

At Tuesday’s hearing, Carter denied a request from Ceglia’s lawyers to authorize warrants for Zuckerberg’s cell phones, email accounts and bank records at Facebook from 2003 to 2004 as overly broad.

He also rejected their bid for Zuckerberg’s Harvard email account and any possible disciplinary records against him for unauthorized use of the school’s computer system.

(Source : Reuters)