A former Mayer Brown executive accused of stealing almost $1 million from the firm may actually have defrauded his former employer of nearly $5 million, according to prosecutors.

David Tresch, the firm's former chief information officer, and alleged co-conspirator Nicholas Demars were charged with 10 counts of mail fraud last week, the Wall Street Journal reports. Federal prosecutors say between 2004 and 2011 the pair ran an elaborate scheme in which Tresch directed Mayer Brown business to Demars, whose company, NS Mater, provided contract workers for the firm's IT department.

In return, Demars allegedly paid Tresch and Tresch's wife millions of dollars in kickbacks. The fraud continued even after Mayer Brown told Tresch to stop using NS Mater's services in 2011, as Demars still sent fake invoices to Tresch for more than $1.1 million in work that he had not completed, investigators say.

The indictment, which was handed down by a federal grand jury in Chicago, seeks the return of $4.8 million from Tresch and Demars, as well as the forfeiture of real estate and vehicles.

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