In April, Attorney General William Barr told a congressional committee that the Justice Department's inspector general was due to release his report on the origins of Russia investigation in May or June. Well into July, the report is still in process and one reason appears to be that investigators working for Inspector General Michael Horowitz deemed information they gleaned from interviewing the author of the infamous Steele dossier meaty enough that they needed to do some follow-up work.
Specifically, Reuters reported Tuesday that "Horowitz’s investigators appear to have found [Christopher] Steele’s information sufficiently credible to have to extend the investigation. Its completion date is now unclear."
The dossier penned by Steele, the former MI6 agent who was hired in 2016 to compile opposition research on Donald Trump, has become the battering ram Trump and his allies have wielded in their quest to discredit the counterintelligence investigation launched by the FBI in July 2016. Their baseless charge is premised on the idea that the FBI relied heavily on the Steele dossier (i.e. opposition research) as a foundation for the probe. The timeline doesn't exactly line up, since the formal investigation started in July and the relevant agents weren't made aware of the dossier until September 19, 2016, according to the New York Times. The September arrival of the dossier did, however, buttress concerns around the Russian contacts of Trump campaign aide Carter Page, who left the campaign around mid-September. The FBI did ultimately cite the Steele dossier in their FISA application to surveil Page, which was approved on Oct. 21, 2016.
But the dossier has proven so central to Trump's criticism of the FBI investigation that the Times reports Horowitz dispatched three Justice Department investigators to interview Steele over the course of two painstaking days of questioning. The investigators reportedly scrutinized everything from Steele's memos at the time to the contemporaneous notes he took during meetings with FBI agents in the fall of 2016. They also queried how Steele verified the legitimacy of his Russian sources and the claims they were making.
The Times wrote a lengthy piece about the IG’s entire investigation process but it was Reuters that reported those efforts yielded enough fruit to delay the Justice Department's final report on how the FBI probe originated. But the IG report is just one of three inquiries into the matter. Both Barr and former Attorney General Jeff Sessions assigned U.S. attorneys to look into the matter.
But the bottom line on the Steele dossier is that while some of the more sordid details have remained unproven, the dossier's central claim was that Russia and Trump's campaign were potentially colluding to win the 2016 election. The report from special counsel Robert Mueller ultimately detailed instances of such collusion between the two entities, even if Mueller did not find enough evidence to prosecute a criminal conspiracy case on those grounds.