The recently declassified referral from the Senate Judiciary Committee, issued by Republican Senators Chuck Grassley and Lindsay Graham, provides new insight into Steele's contacts while he was working on the anti-Trump dossier, revealing that he had written an additional memo, apart from the dossier, using the data received from the Clinton campaign.
The heavily redacted memorandum represents the declassified version of the criminal referral against Steele, which was filed by the senators, saying that Steele was receiving information from "a foreign sub-source" who was in touch with "a friend of the Clintons."
The document unveils the coordination between Clinton's circle and the Obama administration, as part of an effort to source damaging information about then-candidate Trump.
"It is troubling enough that the Clinton Campaign funded Mr. Steele's work, but that these Clinton associates were contemporaneously feeding Mr. Steele allegations raises additional concerns about his credibility," the senators wrote to Deputy Attorney General Rod Rosenstein, who oversees the Russia probe, and FBI Director Christopher Wray.
Controvercial anti-Trump Dossier
The dossier about alleged collusion between Trump's campaign and Russia was first published by BuzzFeed a few days before his inauguration in January, 2017.
The document was written by former British spy Christopher Steele, who was hired by research firm Fusion GPS, which later turned out to have received funding from the Hillary Clinton campaign.
Folowing the publication, in October 2016, The Washington Post reported that the Clinton campaign and the Democratic National Committee (DNC) had helped fund Fusion GPS' research on Trump's alleged ties with Russia.
The Fusion GPS company was originally hired to do research during the 2016 Republican primary campaign for a still unknown Republican donor who wanted to defeat Trump.
The document claimed that the Russian government had compromising information on Trump, which has been denied both by the US president and by Moscow. Almost a year after its publication, the vast majority of the salacious claims contained within remain unverified.
All these publications triggered two separate investigations - dubbed a "witch hunt" by the US president - are currently being conducted by the US Senate and Special Counsel Robert Mueller into the Trump campaign's supposed "collusion" with Moscow, a claim that has been called "groundless" by the Kremlin.