John Durham, the U.S. attorney selected by Attorney General William Barr to examine the origins of the FBI’s investigation into the 2016 Trump campaign’s alleged ties to Russia, has hit the ground running for answers, according to a report.

Durham, a seasoned federal prosecutor from Connecticut, is “very dialed in” to the sweeping review, reports Fox News, citing multiple sources. Durham has also met with Barr “on multiple occasions in recent weeks” in Washington, D.C. and is posing “all the right questions,” according to the news outlet. Further, the hard-nosed U.S. attorney is said to have already received briefings concerning the “four corners” with respect to the bureau’s use of Foreign Intelligence Surveillance Act (FISA) warrants as part of its controversial counterintelligence operation.

“Durham is specifically reviewing the FISA warrant obtained by the FBI to surveil former Trump aide Carter Page, as well as general issues relating to surveillance during the 2016 campaign and matters flowing from the FISA process. Fox News is told Durham would handle the prosecution of any criminal action he might uncover,” Fox News reports.

Although Barr tapped Durham to lead the inquiry last month, he remains directly involved in the probe.

The investigation is examining intelligence and surveillance used during the Russia investigation that spanned President Donald Trump’s presidency for nearly two years. Barr is working with CIA Director Gina Haspel, Director of National Intelligence Dan Coats, and FBI Director Christopher Wray as part of the investigation.

Durham’s appointment came roughly a month after Barr told members of Congress he believed “spying did occur” on the President Trump campaign in 2016. “I think spying on a political campaign is a big deal,” the nation’s chief legal officer testified before the Senate Appropriations Committee, before adding, “I am not suggesting that those rules were violated, but I think it’s important to look at them.”

Last month, President Donald Trump declared his campaign was illegally surveilled, accusing officials responsible of treason. “My Campaign for President was conclusively spied on,” the president wrote on Twitter. “Nothing like this has ever happened in American Politics. A really bad situation. TREASON means long jail sentences, and this was TREASON!”

Durham’s inquiry, which will focus on whether the government’s methods to collect intelligence relating to the Trump campaign were lawful and appropriate, is separate from an investigation by Justice Department inspector general Michael Horowitz. The agency’s watchdog is also examining the Russia probe’s origin, and Barr has said he expects the watchdog report to be done in May or June.

Former Attorney General Jeff Sessions had appointed another U.S. attorney, John Huber, in March 2018 to review aspects of the Russia investigation. The review by Huber, Utah’s top federal prosecutor and an Obama administration holdover, is a “full, complete and objective evaluation” of Republican concerns, Sessions said at the time.

Both the inspector general’s investigation and the probe being conducted by Huber are winding down, the person familiar with the inquiries said.

Durham is a career prosecutor who was nominated for his post as U.S. attorney in Connecticut by President Trump. He has previously investigated law enforcement corruption, the destruction of CIA videotape, and the Boston FBI office’s relationship with mobsters. Durham was unanimously confirmed by the Senate in 2018. At the time, Connecticut’s two Democrat senators, Richard Blumenthal and Chris Murphy, called Durham a “fierce, fair prosecutor” who knows how to try tough cases.

The Associated Press contributed to this report.