In their new book, Glenn Simpson and Peter Fritsch, co-founders of the controversial Fusion GPS opposition research outfit, admit their firm’s infamous anti-Trump dossier was not a “finished product.”

Yet that same dossier reportedly served as a roadmap for the FBI’s investigation into unsubstantiated and unproven allegations of collusion between Russia and Donald Trump’s 2016 presidential campaign. And, according to a Republican House Intelligence Committee memo, the dossier authored by ex-British spy Christopher Steele served as part of the basis for FBI warrant requests under James Comey to conduct surveillance on Carter Page, who served as a tangential adviser to Trump’s campaign.

That memo stated: “Neither the initial application in October 2016, nor any of the renewals, disclose or reference the role of the DNC, Clinton campaign, or any party/campaign in funding Steele’s efforts, even though the political origins of the Steele dossier were then known to senior and FBI officials.”

Fusion GPS was paid for its anti-Trump work by Hillary Clinton’s 2016 campaign and the Democratic National Committee via the Perkins Coie law firm.

The book by Simpson and Fritsch, Crime in Progress: Inside the Steele Dossier and the Fusion GPS Investigation of Donald Trump, was released last week.

The duo claim their dossier was “a series of contemporaneous human intelligence reports—notes from conversations with well-placed sources—intended to inform additional investigation, not to be publicly released and read as a finished product.”

Simpson and Fritch almost seem to gloat about how the dossier’s exposure in the news media, which they insist they were adamantly against, set off a firestorm that tarnished Trump’s presidency.

They wrote the dossier’s public exposure “eventually led to years of congressional investigations and hearings, the firings of National Security Adviser Michael Flynn and FBI Director James Comey, the appointment of special counsel Robert Mueller to what became a nearly two-year criminal investigation, an ongoing counterintelligence investigation, and a swirling brawl between the two political parties that plagued Trump’s term in office from the very first day.”

Ten days before Trump’s inauguration, CNN was first to report the leaked information that the controversial contents of the dossier were presented during classified briefings inside classified documents presented one week earlier to then-President Obama and President-elect Trump. The classified briefings were presented by then-FBI Director Comey, Director of National Intelligence James Clapper, CIA Director John Brennan, and NSA Director Admiral Mike Rogers. Comey reportedly briefed Trump alone on the most salacious charges in the dossier.

CNN cited, “multiple U.S. officials with direct knowledge of the briefings” – in other words, officials leaking information about classified briefings – revealing the dossier contents were included in a two-page synopsis that served as an addendum to a larger report on Russia’s alleged attempts to interfere in the 2016 presidential election.

Prior to CNN’s report leaking the Comey briefing to Trump, which was picked up by news agencies worldwide, the contents of the dossier had been reportedly circulating among some news media outlets, but the sensational claims were not published.

All that changed when the dossier contents were presented to Obama and Trump during the classified briefings. In other words, Comey’s briefings themselves and the subsequent leak to CNN about those briefings by “multiple US officials with direct knowledge,” seem to have given the news media the opening to report on the dossier’s existence, as well as allude to the document’s unproven claims.

Following the CNN report, the full dossier document was published hours later by BuzzFeed.

Aaron Klein is Breitbart’s Jerusalem bureau chief and senior investigative reporter. He is a New York Times bestselling author and hosts the popular weekend talk radio program, “Aaron Klein Investigative Radio.” Follow him on Twitter @AaronKleinShow. Follow him on Facebook.

Joshua Klein contributed research to this story.