Justice Department Inspector General Michael Horowitz is investigating the FBI’s reliance on the unverified dossier produced by British ex-spy Christopher Steele in the surveillance of a Trump campaign associate “despite questions about [Steele’s] credibility.”

Citing unnamed sources, the Wall Street Journal reports Horowitz “is homing in on” and “has been asking witnesses about” the FBI’s “treatment of information” provided by Steele, described as a “key source”, who was used to obtain Foreign Intelligence Surveillance Act warrants against former Trump foreign policy adviser Carter Page.