The Justice Department’s office of the inspector general has conducted more than 100 interviews and reviewed over 1 million records as part of its investigation of the FBI’s use of the FISA process to surveil the Trump campaign, according to a letter obtained by The Daily Caller News Foundation.

In a letter sent to four congressional committees on June 25, Michael Horowitz, the inspector general, said that investigators have made “substantial progress” in the probe, and that “our investigative work is nearing completion.”

“[W]e have been in the process of drafting our report for some time,” he wrote, adding that investigators “have been pursuing opportunities to meet with additional witnesses to ensure that our review is thorough and complete.”

On March 28, 2018, Horowitz began investigating whether the FBI complied with legal requirements in obtaining surveillance warrants against Carter Page, a former Trump campaign adviser. The bureau relied heavily on the infamous and unverified Steele dossier in its applications for the warrants, which were issued under the Foreign Intelligence Surveillance Act (FISA). (RELATED: Christopher Steele Worried He’ll Be ‘Thrown Under The Bus’)

Republicans have accused the FBI of withholding key details about Steele and the dossier in its FISA applications, the first of which was approved on Oct. 21, 2016.

One of the OIG’s most recent interviews was with dossier author Christopher Steele. According to reports published on Tuesday, three attorneys with Horowitz’s office interviewed the former British spy in London in early June.

Horowitz said in his letter that the investigation has been “complicated” by classification issues regarding information obtained in the investigation, was well as the fact that many of its witnesses no longer work in government.

The letter confirms what Texas Rep. John Ratcliffe said in a Fox News interview on July 1. The Republican said that he Horowitz told him a week earlier that the investigation was complete and that a report was being drafted.

“When our draft report is finished, we will follow our usual process to ensure the accuracy, completeness, and appropriate classification of the report. We will update your Committees on our timing and our estimate for completing and issuing a final report when we are able to do so,” Horowitz wrote, adding that he anticipates being able to provide an update “in the coming weeks.”

Michael Horowitz letter to Congress, June 25 by Chuck Ross on Scribd

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