New Jersey Gov. Chris Christie's law firm hired a digital forensics firm that has so far billed taxpayers more than $2.2 million as part of the ongoing Bridgegate case, according to invoices dating back to January 2014 and released Friday night by the Attorney General's Office.

That means the public's tab for Bridgegate legal expenses now totals $13,665,459.50, with more than $10 million going to represent the governor's office.

That total, compiled by WNYC, includes more than $8 million for the Gibson Dunn law firm, which exonerated Christie as part of a taxpayer-funded internal investigation and now represents his office in the ongoing Bridgegate case. More than $1.2 million has been spent on legal bills for state employees. The Democratic-controlled legislative investigative committee paid its outside counsel $1.2 million, and the Port Authority of New York and New Jersey, which relies on toll collections at the bridge and tunnels into New York for much of its revenue, is paying lawyers for several employees whom it has not identified. 

The latest bills come from Stroz Friedberg, a company that does digital forensics and investigative work. The state revealed Friday night that Stroz Friedberg was hired by Gibson Dunn, at taxpayers' expense, to find and collect documents in order to respond to subpoenas from the state legislature and US Attorney's Office stemming from the 2013 lane closures at the George Washington Bridge. The tab started in January 2014 and goes through the end of 2015. The fact that it has been doing work for two years was only revealed following an open records request from The Bergen Record.

Like the release of previous invoices, this one came after business hours on a Friday from the Attorney General's Office, which is supposed to be independent from the governor's office. Representatives for the agencies didn't answer questions about whether the timing of the release was coordinated to minimize media coverage.

The electronic retention of documents by Christie's office has become a key issue in the upcoming Bridgegate trial, where two former Christie appointees face charges. US District Judge Susan Wigenton has said that Christie's lawyers effectively shredded documents by failing to retain notes from interviews it conducted with the governor and others as part of the internal investigation that exonerated Christie of wrongdoing in the matter.

Two former Christie appointees were charged in the lane closures scheme and face trial in May. Their lawyers say that Christie's legal team is hiding thousands of documents, including the governor's own emails and correspondence sent between Christie allies during the week of the lane closures. Earlier this month, Wigenton ordered the release of Christie's cell phone records and other documents. 

Only one email from Christie about Bridgegate has ever publicly been released. Text messages he sent during a key legislative hearing into the matter were deleted and have not been recovered.

Christie has repeatedly defended the internal investigation by Gibson Dunn as independent. But 28 of its attorneys donated to his presidential campaign, and one of the attorneys who interviewed him was a top supporter, a personal friend and fundraiser.

Gibson Dunn is apparently still retained by the governor's office but hasn't submitted invoices since August.

Christie's 2013 gubernatorial campaign also retained Stroz Friedberg as it faced its own subpoenas. But the campaign hasn't paid its $362,000 bill, leading one Democrat, Assemblyman John Wisniewski, to allege that Christie is effectively able to "wash away the debt by giving them work through the governor’s office."