When Igor Danchenko, the main source for the Steele Dossier, told the FBI that he couldn't corroborate the information in the dossier, that should have closed the case. The FBI and the Department of Justice had based their entire case on key information in the dossier. They never corroborated it. And now that they knew the main source couldn't back it up either, did they tell the FISA Court? And, if so, what did they tell the FISA Court.
The Inspector General's report lays out what happened next. The FISA Court was told that Danchenko had been "truthful and cooperative" during his interview. The FISA Court was not told that Danchenko blew a hole in the government's case. Who lied to the FISA Court? Did the government's lawyers knowingly lie? If not, who told them that Danchenko was "truthful and cooperative."
As it turns out, the FBI's lawyers were never briefed on the Danchenko interview. They said that members of the Crossfire Hurricane team led them to believed that Danchenko “essentially echoed,” “was consistent with,” or “corroborated” the dossier. Of course none of that was true.