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Former Republican Rep. Denver Riggleman of Virginia — who served as a senior technical adviser to the House select committee probing the Jan. 6, 2021, assault on the Capitol — is working with the legal team advising President Biden’s son, Hunter Biden, who is facing increasing scrutiny from House Republicans over his business dealings. 

Riggleman’s work with Hunter Biden is focused on assessing data issues, and he has assisted Biden’s lawyers as they contend with congressional inquiries and evaluate GOP claims made about his conduct, according to three people with knowledge of the Biden legal team. 

Riggleman’s work with Hunter Biden was confirmed on Tuesday by Kevin Morris, a lawyer and confidant of the president’s son. 

“Denver has been assisting us with data analysis since late last year,” Morris said in a statement to CBS News. “He is an invaluable resource and we have made tremendous strides in untangling the massive amount of corruption and disinformation involved in this story. There will be much more coming to the public.” 

Riggleman said in a statement Tuesday that he and his associates are working with Hunter Biden’s attorneys. 

“I and my forensics, data, and telephony team are conducting data investigations and analysis for Hunter Biden’s legal team,” Riggleman said, with a concentration on “data across the spectrum.” 

Riggleman’s efforts have brought him into Hunter Biden’s circle, and he has also provided the president’s son with insights into House Republicans and their methods, those with knowledge of the Biden legal team said. 

On Monday, they said, Riggleman was at a hotel in Washington, D.C., for a meeting with Hunter Biden’s lawyers. And on Tuesday evening, he was at the White House as one of the members of the Hunter Biden team invited to celebrate the July Fourth holiday. 

For Hunter Biden, the coming months could be a critical period. Although a plea agreement with federal investigators was announced last month on tax fraud and gun possession charges, congressional Republicans have expressed outrage about the deal, vowing to move forward with their own investigations separate from the Justice Department’s probe. 

Riggleman’s work with Hunter Biden’s team has included reviewing Republican claims related to a laptop that the lawyer for a Delaware computer repair shop owner says was left by Hunter Biden in 2019, which was later provided to the FBI under subpoena. 

CBS News last year was provided a copy of that data by the lawyer for the repair shop and conducted an independent analysis led by two cyber investigators from Minneapolis-based Computer Forensics Services.

Riggleman has spent months, those with knowledge said, providing digital forensic analysis for the Biden legal team on whether any data linked to Hunter Biden, such as text messages, has been distorted or fabricated. Data from the left-behind laptop and bank records remain key elements of the Republican investigation of the Biden family.  

Riggleman, a 53-year-old former Air Force intelligence officer — and former member of the conservative House Freedom Caucus — has become a fierce critic of former President Donald Trump in recent years, and a frequent commentator, where he has argued that far-right extremism and conspiracy theories present a threat to American democracy. His book, “The Breach,” dealt with those issues, and with his work for the House select committee.  

In an appearance last year on “60 Minutes,” Riggleman suggested that the Trump White House should be further investigated for any possible communications between officials and Jan. 6 rioters. 

“The thing is, the American people need to know that there are link connections that need to be explored more,” Riggleman said. 

Riggleman joined the Jan. 6 committee months after leaving the House in early 2021, following a single term representing the Charlottesville area. During his two years in Congress, Riggleman clashed with local conservatives over his decision to officiate a same-sex wedding, and was defeated by a conservative challenger at a nominating convention in 2020.

At the start of his work with the Jan. 6 committee, Riggleman and several committee members developed a bond as he combed through reams of data, and mapped out text messages obtained from Trump allies, such as former White House chief of staff Mark Meadows. But tensions about the committee’s strategy, and the scope of its investigation, eventually led Riggleman to leave his position.  

Riggleman’s frustrations about the committee became public around the publication of “The Breach” last year. At the time, a spokesman for the committee said any assertion that the committee was not being aggressive in investigating Jan. 6 was false and misleading, pointing to its then upcoming final report as a comprehensive document. 

In the coming months, GOP investigations of Hunter Biden are likely to coincide with the presidential campaign as Republican contenders begin to appear at debates, and Mr. Biden ramps up his reelection bid.

In June, Delaware U.S. Attorney David Weiss announced that a plea agreement had been reached with Hunter Biden, potentially avoiding incarceration or a trial over two misdemeanor tax offenses and a felony firearm offense. A federal judge must first approve the deal, and a hearing has been scheduled for July 26. 

Most House Republicans have responded to the announced agreement by claiming they believe the Justice Department gave Hunter Biden a favorable deal due to his relation to the president.   

“My first reaction is that it continues to show a two-tiered system in America,” House Speaker Kevin McCarthy, a California Republican, said last month. “If you are the president’s son, you get a sweetheart deal.”

McCarthy has encouraged the House Oversight Committee, chaired by Republican Rep. James Comer of Kentucky, to keep up its investigation of the business dealings of Mr. Biden’s family. 

Biden’s lawyers have accused House Republicans of trying to derail the plea agreement.  

As they move forward, House Republicans have also pointed to comments made by the IRS supervisory agent who helped oversee the investigation of Hunter Biden — and one of two whistleblowers who raised concerns about how the DOJ probe was conducted, saying the IRS whistleblower’s allegations necessitate further investigation. 

“We have to make sure as a special agent for IRS Criminal Investigation that we treat every single person exactly the same,” Gary Shapley, a 14-year veteran of the agency, told CBS News chief investigative correspondent Jim Axelrod last month. “And that just simply didn’t happen here.”

Hunter Biden’s criminal attorney, Christopher Clark, did not respond to requests for comment about Shapley’s remarks, but in a statement at the time the plea arrangement said that “as his attorney through this entire matter, I can say that any suggestion the investigation was not thorough, or cut corners, or cut my client any slack, is preposterous and deeply irresponsible.”