The federal prosecutor running the Justice Department's review of the origins of the Russia investigation has expanded the inquiry that critics have panned as an effort to discredit special counsel Robert Mueller's work.

After months of investigating, U.S. Attorney John Durham has broadened his team to include additional agents and resources as the timeline they are examining has extended, according to Fox News.

The investigation of the investigators, led by Attorney General William Barr and Durham as his right-hand man, had targeted the beginning of the Trump-Russia counterintelligence investigation to the 2016 election. It has been elongated to include at least the spring of 2017, when former FBI Director Robert Mueller was appointed special counsel after former FBI Director James Comey was fired by Trump and leaked the contents of some of his memos to the media.

Durham's team has been focusing so far on the FBI's reliance on informants, some of whom, such as Cambridge professor Stefan Halper, made contact with members of the Trump campaign. Durham may also be looking into alleged Foreign Intelligence Surveillance Act abuses.

The 412 pages of redacted FISA documents released in 2018 show that the DOJ and the FBI made extensive use of an unverified dossier compiled by British ex-spy Christopher Steele, which made a series of allegations regarding Trump and Russia. Steele put his research together in 2016 at the behest of Fusion GPS, which had been hired by the Clinton campaign and the Democratic National Committee through the Perkins Coie law firm. The funding Steele received from a Democratic presidential campaign was not revealed to the FISA Court.

The Barr-Durham investigation is separate from the one just finished by DOJ Inspector General Michael Horowitz. The DOJ watchdog investigated allegations of FISA abuse by the DOJ and the FBI, and Horowitz has spoken with Durham, who is handling any criminal referrals from Horowitz’s investigation.

Barr testified to the Senate in April he believed “spying did occur” against the Trump campaign and said while he wasn’t “suggesting it wasn't adequately predicated,” it was his obligation to explore it. Barr promised he would “be reviewing both the genesis and the conduct of intelligence activities” during the 2016 election, and Trump gave him “full and complete authority to declassify information pertaining to this investigation” the following month. Barr selected Durham lead the effort soon after.

Barr praised Durham in May, saying, “He has, over the years, been used by both Republican and Democratic attorneys general to investigate these kinds of activities. And he's always gotten the most laudatory feedback from his work. So there's no doubt in my mind that he's going to conduct a thorough and fair review of this.”

DOJ spokeswoman Kerri Kupec said earlier this month that the DOJ was exploring whether any foreign intelligence services played a role in the counterintelligence investigation directed against Trump’s campaign.

“Mr. Durham is gathering information from numerous sources, including a number of foreign countries,” Kupec said. “At Attorney General Barr’s request, the president has contacted other countries to ask them to introduce the attorney general and Mr. Durham to appropriate officials.”

Soon after the transcript of a July 25 phone call between Trump and Ukraine’s president was released, a call between Trump and Australia’s prime minister was also made public, revealing that Trump had encouraged Australia to cooperate with Barr in his Trump-Russia origins investigation.

Barr also discussed the investigation with the United Kingdom and Barr traveled with Durham to Rome to meet with Italian intelligence officials as part of the effort. The duo are likely seeking information related to key Trump-Russia figures, including: Steele, whose dossier was used to obtain secret surveillance warrants against Trump campaign associate Carter Page; Australian diplomat Alexander Downer, whose tip about former Trump campaign foreign policy adviser George Papadopoulos telling him the Russians had damaging information on Hillary Clinton led the FBI to officially open the Trump-Russia counterintelligence investigation; and mysterious Maltese academic Joseph Mifsud, who allegedly told Papadopoulos that Russia had dirt on Clinton.

Reaching out to foreign governments for help in DOJ-run investigations is not uncommon. As part of his probe, Mueller made 13 requests to foreign governments for evidence.

The report from Horowitz’s investigation is expected by the end of October, but it is not known when the Barr-Durham inquiry will conclude.