Just before Christmas 2015, the British intelligence operative Christopher Steele emailed a report to private clients that included an American lawyer for a Ukrainian oligarch.

The title of the dossier was “FIRTASH Abortive Return to Ukraine,” and it purported to provide intelligence on why the energy oligarch Dmitri Firtash tried, but failed, to return to his home country of Ukraine.

“FIRTASH’s talk of returning to Ukraine a genuine ambition rather than merely a ruse to reveal Ukrainian government’s hand. However the oligarch developed cold feet upon the news of a negative reception at Boryspil airport,” Steele reported on Dec. 23, 2015.

Perhaps most important to the recipients, the former MI6 agent’s report purported to share the latest thinking of Russian and U.S. officials on Firtash, who at the time faced U.S. criminal charges and was awaiting extradition from Austria.

Those charges and extradition remain unresolved four years later. Firtash insists on his innocence, while the U.S. government stands by it case despite recent criticism from Austrian and Spanish authorities.

“The prevarication over his return has lost FIRTASH credibility with the Russians, but his precarious position in Austria leaves him little choice but to acquiesce with Moscow’s demands,” the Steele report claimed. “Separate American sources confirm that US Government regards FIRTASH as a conduit for Russian influence and he remains a pariah to the Americans.”

The anecdote of the Firtash report underscores that challenges the FBI faced when it used Steele in 2016 as a human source in the Russia collusion probe.

He not only opposed Trump and was paid by Hillary Clinton’s opposition research firm to dig up dirt on the then-GOP nominee, he also was in the business of selling intelligence to private clients – all perfectly legal — while informing for the FBI.

Steele had engaged the U.S. government on occasion since his retirement from MI6 in 2009, both as an FBI informant in the FIFA soccer corruption case and as intelligence provider to the Obama State Department. So any assessment he offered from U.S. officials was closely watched by private clients.

His Firtash report cited an unnamed intelligence source indicating that Firtash had little chance of winning any favor under the Obama administration, but that other oligarchs in the region might be welcomed by the Americans if they sought to play a role in Ukraine.

“The source had a separate confirmation from US sources that Washington regarded FIRTASH as a conduit for Russian influence,” the report said. “Whilst the USG was prepared to do business with the likes of Rinat AKHMETOV and Ihor KOLOMOISKY, FIRTASH remained a pariah.”

The U.S. lawyer who received Steele’s report represented Firtash and had spent part of 2015 checking whether there was an opportunity the State or Justice Department might negotiate to settle the criminal case against his client. He determined the U.S. government did not, something Steele’s report only affirmed anew.

Steele did not immediately respond to a message to his London business office seeking comment. But his firm has issued a blanket statement on its Web site saying it does highly professional work but doesn’t comment on specific clients or products.

“Orbis Business Intelligence has an established track record of providing strategic intelligence, forensic investigation and risk consulting services to a broad client base,” the firm wrote. “The nature of our business, and our high standards of professionalism dictate that we would not disclose to the public information on any specific aspects of our work. We remain fully committed to the secure provision of our services to our clients and partners worldwide.”

Steele and his infamous dossier alleging an unfounded conspiracy between Donald Trump and Vladimir Putin to hijack the 2016 election are expected to play a starring role in a long-awaited Justice Department inspector general’s report reviewing the FBI’s Russian collusion probe.

The report to be made public next month is expected to reveal that one FBI official falsified a document and other U.S. officials withheld information both about Steele and the innocence of some of the targeted individuals when the FBI sought a Foreign Intelligence Surveillance Act warrant to probe the Trump campaign’s ties to Russia starting in October 2016.

Some intelligence experts have been quoted recently as saying Steele’s information against Trump, much of which the FBI could never verify, may have been Russian disinformation designed to sow chaos during the U.S. election.

After two-plus years of investigation, Special Counsel Robert Mueller concluded this spring that there was no collusion or conspiracy between Russia and the Trump campaign. Nonetheless, the allegations have lingered over the Trump presidency and divided the country bitterly.

Steele’s Firtash report is a cogent reminder that while Steele on occasion worked for the U.S. government, he also was simultaneously pitching intelligence he got from American sources and others to his private clients, some who had different interests than the United States.

The back and forth between U.S. and other contacts in Steele’s business was laid bare by email and text messages released by the Justice Department last year. For instance, the messages show that less than three weeks after emailing the Firtash report, Steele reached out in January 2016 to senior U.S. Justice Department official Bruce Ohr, a prosecutor with responsibility for Eurasian oligarchs, to set up a possible meeting in London.

Steele and Ohr had frequent contact all the way through 2017, including when Steele shared on July 30, 2016 some of his anti-Trump evidence with Ohr, who then took it to the top of the FBI. Steele was eventually dropped by the FBI as an informant for leaking to the news media.

Fiona Hill, a recent impeachment witness and a former top Russia expert on the National Security Council, suggested to lawmakers in a deposition recently that Steele’s dual role as government insider/informer and private intelligence provider left him vulnerable to Russian disinformation when he wrote his dossier.

“He was constantly trying to drum up business,” Hill testified when asked about her own contacts from time to time with the former British intelligence agent.

She said that when she read Steele’s anti-Trump dossier in January 2017 she instantly feared it might be disinformation fed to Steele by the Russians because he previously had done spy work for MI6.

“That is when I expressed the misgivings and concern that he could have been played,” Hill testified.

She added: “The Russians would have an axe to grind against him given the job he had previously. And if he started going back through his old contacts and asking about that, that would be a perfect opportunity for people to feed him some kind of misinformation.”

The IG report set to be released Dec. 9 will give Americans a more comprehensive look at Steele and the FBI’s reliance on him as an informant.

And then it will be up to the FBI, DOJ and congressional oversight committees to re-evaluate what lessons can be learned from the now-debunked Russia collusion probe.

Those likely are to include better vetting of informants, stronger oversight of the FISA process and new regulations for when the FBI can investigate a candidate during the middle of an election, especially when the allegations emanate from a political opponent.