If the man Christopher Steele relied on as a source for his dossier had come under even cursory scrutiny, his material would have been rejected and the whole Russiagate investigation would have been have been shut down. From Paul Sperry at realclearinvestigations.com:
The mysterious “Primary Subsource” that Christopher Steele has long hidden behind to defend his discredited Trump-Russia dossier is a former Brookings Institution analyst — Igor “Iggy” Danchenko, a Russian national whose past includes criminal convictions and other personal baggage ignored by the FBI in vetting him and the information he fed to Steele, according to congressional sources and records obtained by RealClearInvestigations. Agents continued to use the dossier as grounds to investigate President Trump and put his advisers under counter-espionage surveillance.
The 42-year-old Danchenko, who was hired by Steele in 2016 to deploy a network of sources to dig up dirt on Trump and Russia for the Hillary Clinton campaign, was arrested, jailed and convicted years earlier on multiple public drunkenness and disorderly conduct charges in the Washington area and ordered to undergo substance-abuse and mental-health counseling, according to criminal records.