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U.S. Attorney David Weiss, the federal prosecutor who faced backlash after announcing a probation-only plea agreement for Hunter Biden in July, will now serve as a special counsel in the ongoing investigation into the president's son.

Weiss was appointed as special counsel in the probe by Attorney General Merrick Garland on Friday, marking the latest development in the closely watched investigation into Hunter Biden's business dealings.

House Oversight Committee Chairman James Comer, R-Ky., called Garland's announcement "part of the Justice Department’s efforts to attempt a Biden family coverup in light of [House Oversight Republicans'] mounting evidence of President Biden’s role in his family’s schemes selling ‘the brand’ for millions of dollars to foreign nationals."

Before Weiss' move into the new role, congressional Republicans blasted his proposed plea agreement for Hunter Biden as a "sweetheart" deal, and critics alleged the Department of Justice is operating under a two-tier justice system — a charge that Garland has denied.

AG GARLAND APPOINTS HUNTER BIDEN INVESTIGATOR DAVID WEISS SPECIAL COUNSEL

Weiss and the Bidens

David Weiss, inset, Hunter Biden and President Biden. (Fox News)

Weiss defended his probe of Hunter’s financial dealings after he announced in June that Hunter had agreed to plead guilty to two misdemeanor tax violations and enter into a diversion program for a felony gun charge, keeping him out of jail.

Weiss also denied claims by two IRS whistleblowers who alleged officials at the Justice Department, FBI and IRS interfered with Weiss’ five-year investigation into President Biden’s son.

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Weiss, a Philadelphia native, began his legal career in 1984 as a law clerk to Justice Andrew D. Christie of the Delaware Supreme Court. 

Though Weiss is a registered Republican, it doesn’t appear that he’s made any significant political donations, according to Federal Election Commission records.

Weiss David

U.S. Attorney David Weiss. (Fox News screenshot)

Weiss served as an assistant U.S. attorney from 1986 through 1989, where he prosecuted corruption, money laundering, and mail and wire fraud. He then spent a decade in the private sector, taking top positions at Duane Morris and The Siegfried Group, before he returned to serve as the first assistant U.S. attorney.

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In November 2017, Weiss was nominated as U.S. attorney by then-President Donald Trump after he was recommended by Sens. Tom Carper and Chris Coons, who are both Delaware Democrats.

"David is a career prosecutor and dedicated public servant, longtime Delawarean, and valued member of our law enforcement community," Coons said at the time. "I want to thank the White House for working with Sen. Carper and me to present an excellent nominee for U.S. attorney."

Weiss was later confirmed by the Senate and sworn in as the attorney for the U.S. District Court for the District of Delaware on Feb. 22, 2018. 

In February 2021, shortly after President Biden took office, the DOJ pressured Trump-appointed U.S. attorneys to resign, but Weiss was asked to stay on due to the Hunter Biden probe, which began sometime in 2018.

IRS agent Gary Shapley sits down on the Fox News Channel "Special Report" set for an interview

IRS Criminal Supervisory Special Agent Gary Shapley Jr. defended his claims that the Justice Department interfered with U.S. Attorney David Weiss' Hunter Biden investigation in an interview with Fox News' "Special Report."  (Fox News)

Sen. Lindsey Graham, R-S.C., the ranking member of the Senate Judiciary Committee, sent letters to Weiss and Garland in June, demanding answers amid allegations from the whistleblowers suggesting the probe was slow-walked and influenced by politics.

The whistleblowers alleged in testimony before the House Ways and Means Committee that Weiss was "constantly hamstrung, limited, and marginalized by DOJ officials as well as other U.S. Attorneys." They testified that Weiss had requested to have special counsel authority, but was denied.

"It is imperative these allegations are addressed head-on," Graham wrote to Garland, questioning whether he was "aware of any request" by Weiss to be designated special counsel.

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Weiss responded in a letter Monday, saying he had not requested special counsel designation and reiterating that he has "never been denied the authority to bring charges in any jurisdiction."

The Justice Department has also denied the whistleblowers’ claims, with Garland saying Weiss was "given complete authority to make all decisions on his own behalf." 

Fox News’ Houston Keene, Aubrie Spady, Brooke Singman and the Fox News Brainroom contributed to this report.