What the Murdochs need right now are some mob lawyers. They should have discreet counsel on how to limit exposure, on what to do and say if they are arrested, and maybe the occasional use of an unbugged room in which to conduct business under the protection of the attorney-client privilege. Instead, what the family is getting is less Corleone consigliere, more Fredo Corleone rat.

The U.K. firm Harbottle & Lewis is leading the charge of lawyers aggressively dropping a dime on News International. Newly released documents in the hacking case show former staff lawyers Jon Chapman and Tom Crone both turning on their former bosses, and the Murdochs must now fear the worst over BCL Burton Copeland, the City firm drafted by their company to conduct a nine-month internal investigation into criminality.

Harbottle has been paid coming and going in the hacking scandal. The firm first advised Prince William and Kate Middleton over the investigation of erstwhile News of the World royals reporter Clive Goodman. The Scotland Yard probe ended in Goodman’s imprisonment for hacking the phones of members of the royal household, and with an apology and offer of a substantial donation to charities of Prince William’s choosing from News International.

Then Harbottle switched sides, acting for News International over a wrongful-dismissal claim by Goodman in 2007. Goodman’s claim rested on the allegation that phone hacking was widespread at News of the World. Harbottle was drafted to refute this and, working with a number of supplied emails, found no evidence of a wider conspiracy to hack phones. Harbottle sent a letter to this effect, which over the next several years News International brandished like O. J. Simpson’s leather glove, using it to rebuff reporters and politicians alike.

Indeed, the company clung to the letter long after a wider conspiracy had been publicly established. At July’s dramatic select-committee hearing, the Murdochs once again trotted out the Harbottle opinion, this time using it to defend their decision not to investigate further. James Murdoch even swiped at Harbottle, saying the firm made a “major mistake” in characterizing the hacking as being confined to Goodman.

This week Harbottle forcefully came out against News International. In a letter to the select committee, the firm rejected “News Int’s self-serving view of the firm’s role in events.”

Harbottle stated that it had charged just £10,000 for a “narrow” scope of work that involved only analyzing a series of emails for criminal liability. The investigation was “short, limited in terms of access to documents,” and “without any access at all to witnesses.”

Rupert Murdoch’s characterization of the job—that Harbottle was brought in “to find out what the hell was going on”—was “misleading,” the firm added. Twisting the knife further, Harbottle claimed the 2007 letter was never intended for publication, a detail that makes News International look ever more duplicitous.

But Harbottle is not a lone snitcher. News International’s former head of corporate and legal affairs, Jon Chapman, has broken ranks too. Chapman was instrumental in marshaling the company’s defense in the hacking scandal, helping to set the terms of the internal investigation. But in an Aug. 11 letter to the select committee, Chapman wrote that the testimonies of both Rebekah Brooks, the former News of the World editor and top News International executive, and the two Murdochs contained “serious inaccuracies.”

Meanwhile, Tom Crone, former chief lawyer for News of the World, is embroiled in increasingly confrontational correspondence with James Murdoch via the select committee, over Murdoch’s claim that Crone and former NotW editor Colin Myler failed to inform him about widespread hacking.

Murdoch has doubled down on statements he made in the hearing, with a written statement insisting that “neither Mr Myler nor Mr Crone told me wrongdoing extended beyond Mr Goodman or [private detective Glenn] Mulcaire.” But Crone, in new written evidence, all but accuses his old boss of lying about this.

“I have no doubt that I informed Mr. Murdoch of its existence, of what it was and where it came from,” he wrote.

All this is small beer compared with the supergrass that BCL Burton Copeland may turn out to be.

It was previously known that the London City firm, which specializes in commercial fraud and business crimes, was liaising with the police on behalf of News International. But the letters released Tuesday by the select committee focus on the firm’s nine-month investigation into the criminal activity at the company in 2006.

In his evidence to the select committee back in 2009, Crone described Burton Copeland’s involvement: “Burton Copeland were in the office virtually every day or in contact with the office every day,” and the firm's lawyers “looked at all of the financial records; and there was subsequently an email check done which went to 2,500 emails.”

Yet Burton Copeland is conspicuously absent in the Murdochs’ July hearing evidence. Crone wondered in his letter why such focus is put on the “relatively limited” Harbottle 2007 email review, while News International is no longer referring to the Burton Copeland investigation.

In its letter, Harbottle suggested the committee ask the company to waive its client confidentiality and let Burton Copeland share its findings.

If there is any further evidence of a cover-up, this firm is likely to have it—and fatally undermine the Murdochs’ claims of blissful ignorance. For the family’s sake, someone had better be organizing a horse’s head for the Burton Copeland offices before it’s too late.