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Facebook attorneys late Monday revealed evidence that they say proves a New York man fabricated a contract that he says entitles him to part ownership of the $50 billion social network.

Included in an after-hours court filing is an image of a two-page contract signed by Paul Ceglia of Wellsville, New York, and Facebook founder Mark Zuckerberg recovered by forensics experts from Ceglia's computer. The image is blurry and difficult to read but appears only to refer to a street-mapping database Ceglia hired Zuckerberg to work on in 2003 -- and not Facebook.

Ceglia's lawsuit against Zuckerberg is based on a contract that he says shows that when he hired Zuckerberg for the streets project, he also invested $1,000 in the then-Harvard University student's fledgling Facebook idea on the condition he'd own half if it expanded.

From the beginning, Facebook has said the contract submitted by Ceglia was doctored. Now, attorneys said, they've got the original, retrieved from embedded electronic data.

Facebook alluded to the find as "smoking gun" evidence in earlier court filings but was barred from publicly identifying it by a confidentiality order which has since been modified.

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"This smoking gun evidence confirms what defendants have said all along: the purported contract attached to the complaint is an outright fabrication," attorney Orin Snyder of Gibson, Dunn & Crutcher LLP, wrote Monday.

Ceglia's attorney, Jeffrey Lake of San Diego, did not respond to an emailed request for comment from The Associated Press Monday night. Ceglia is in Ireland, according to emails he's written to his hometown newspaper, the Wellsville Daily Reporter.

In court papers filed last week, Ceglia's attorneys took issue with Facebook's claims that Ceglia had concealed certain documents.

"No good-faith basis has been shown for such an accusation," Lake wrote.

He said Cegla had complied with the court's instructions to turn over all of his computers and electronic media as part of the discovery process in the case.

Zuckerberg's lawyers say six removable storage devices containing files entitled "Zuckerberg Contract" and "Facebook Files" are missing.

The lawyers are scheduled to appear before U.S. Magistrate Judge Leslie Foschio in Buffalo on Wednesday to argue a series of motions. Ceglia wants the judge to compel Facebook to turn over emails between Ceglia and Zuckerberg captured from Zuckerberg's Harvard account from 2003 and 2004. He's also asked that the case be sent to mediation for possible settlement to avoid protracted proceedings.

Facebook wants the judge to require Ceglia to produce the original electronic version of the contract and other electronic files and to allow further ink sampling from a hard-copy version of the contract.

Zuckerberg's attorneys oppose mediation as "pointless," saying the only resolution to the case they're willing to accept is to see it thrown out.

View the original case documents, obtained by FoxNews.com:

Declaration of Dr. Albert Lyter III

'Work for Hire' Contract

Fake 'Work for Hire' Contract 

Declaration of Alexander H. Southwell

Defendant's Reply

Street Fax