An idle threat? Probably not. Fox News has hired formidable legal help for its counter-attack on Gawker and its so-called “Fox Mole” — disclosed last night to be Joe Muto, who worked on The O’Reilly Factor before he was discovered and fired. Ronald Green of Epstein Becker & Green specializes in helping companies deal with unhappy employees. He defended Bill O’Reilly in his 2004 sexual harassment case that was settled before it went to court. Green’s page on his company’s site describes him as “one of the pioneers of the use of preemptive litigation in suing current and former employees, and others” who threaten to extort companies. He’s also said to be “an innovator in the use of federal Declaratory Judgment Act” to help clients who “may be at risk from disaffected employees.” His client list includes lawyer David Boies, the New York Knicks, and NBC.

But Gawker doesn’t seem to be intimidated. It posted Green’s letter to publisher Nick Denton today even though it was labeled “Not For Publication.” The letter warned that Muto admitted to “likely criminal and civil wrongdoing on both his and Gawker’s part, which will be the subject of further extensive investigation.” Green told the website to “immediately stop publishing” and return to Fox “information and videos that have been unlawfully obtained.” He also wants Denton to “preserve all documents and information” about Gawker’s employment of Muto including information “for possible future publication.” Green says that Fox “will pursue its rights and remedies in the appropriate legal forums.” Forbes reports that Gawker paid Muto $5,000 for his work.