Mr. Horowitz’s report, which is most likely to be made public in the coming weeks, is expected to criticize law enforcement officials’ actions in the Russia investigation. Mr. Horowitz’s findings could provide insights into why Mr. Barr thought that the Russia investigation needed to be examined.
Mr. Durham’s questions seem focused on elements of the conservative attacks on the origins of the Russia inquiry. It is not clear whether he has asked about other parts of the sprawling investigation, which has grown to include more than 2,800 subpoenas, nearly 500 search warrants, 13 requests to foreign governments for evidence and interviews of about 500 witnesses.
In his review, Mr. Durham has asked witnesses about the role of Christopher Steele, a former intelligence official from Britain who was hired to research Mr. Trump’s ties to Russia by a firm that was in turn financed by Democrats. Law enforcement officials used some of the information Mr. Steele compiled into a now-infamous dossier to obtain a secret wiretap on a Trump campaign adviser, Carter Page, whom they suspected was an agent of Russia.
The president and his supporters have vilified Mr. Steele, saying that investigators should have kept his information out of the application for the wiretap because they viewed him as having a bias against Mr. Trump. The Steele information served as one piece of the lengthy application.
They have accused the F.B.I. and Justice Department of failing to disclose that Democrats were funding Mr. Steele’s research, but the wiretap application contains a page-length explanation alerting the court that the person who commissioned Mr. Steele’s research was “likely looking for information” to discredit Mr. Trump.
Mr. Durham’s investigators asked why F.B.I. officials would use unsubstantiated or incorrect information in their application for a court order allowing the wiretap and seemed skeptical about why agents relied on Mr. Steele’s dossier.
The inspector general has also raised concerns that the F.B.I. inflated Mr. Steele’s value as an informant in order to obtain the wiretap on Mr. Page. Mr. Durham’s investigators have done the same, according to the people familiar with his review.