Two veteran I.R.S. investigators leveled harsh criticism on Wednesday against the Justice Department over its handling of the tax case against Hunter Biden, accusing the agency of shielding him from felony charges because of politics and preferential treatment.
During an hourslong hearing of the House Oversight Committee, the investigators, Gary Shapley and Joseph Ziegler, detailed how they believed their work investigating Mr. Biden, the president’s son, was stymied and slow-walked by Justice Department officials during both the Trump and Biden presidencies.
“There should not be a two-track justice system based on who you are and who you’re connected to,” said Mr. Shapley, a special agent in the I.R.S. criminal division for 14 years. “Yet in this case, there was.”
Mr. Biden struck a deal with the Justice Department to plead guilty to two misdemeanor tax charges and accept terms that would allow him to avoid prosecution on a separate gun charge, but the investigators said they had recommended felony charges against him.
“As the special agent on this case, I thought the felony charges were well supported,” Mr. Ziegler, the lead I.R.S. case agent on the Hunter Biden investigation told Congress.
Mr. Ziegler described a litany of Mr. Biden’s tax offenses: falsely claiming business deductions for payments made to the Chateau Marmont in Los Angeles, a hotel room for his drug dealer, a sex club membership and a Columbia University tuition payment for his adult daughter.
“I still think that a special counsel is necessary for this investigation,” he added.
Before regaining control of the House this year, Republicans pledged to use their power to investigate President Biden and his family, launching wide-ranging inquiries. It was clear from their approach on Wednesday that House Republicans believe the testimony from the two I.R.S. officials is their most impactful evidence to date.
Three committee chairmen — Representatives James R. Comer of Kentucky who heads the Oversight panel; Jim Jordan of Ohio from the Judiciary Committee; and Jason Smith of Missouri from the Ways and Means panel — joined forces to lead the questioning of witnesses during the hearing.
But if the proceeding at times was a sober recounting of facts and details from a high-profile but secretive investigation, it also veered into rank partisanship, hyperbole and — in a spectacle seldom seen in a Capitol Hill hearing room — sexually explicit material.
Representative Marjorie Taylor Greene, the right-wing Republican from Georgia, displayed naked photos of Hunter Biden engaging in sex acts as she questioned whether the evidence found on his laptop that he solicited prostitutes amounted to human trafficking.
“Viewer discretion is advised,” she warned before launching into her presentation.
“Should we be displaying this in the committee?” asked Representative Jamie Raskin of Maryland, the top Democrat on the panel, after Ms. Greene had held up several blown-up photographs and video screenshots.
Democrats repeatedly expressed disgust at the tenor of the hearing, and the White House condemned it.
“Despite years of obsession and countless wasted taxpayer dollars on a wild goose chase, the @HouseGOP hasn’t offered a single credible piece of evidence of wrongdoing by the President,” Ian Sams, a White House spokesman, wrote on Twitter. “This waste of time reflects the extraordinarily misplaced priorities of House Rs.”
Mr. Shapley accused both Attorney General Merrick B. Garland and David C. Weiss, the U.S. attorney in Delaware, of stating falsely that Mr. Weiss had been fully empowered to pursue the Hunter Biden — allegations both men have denied.
Mr. Weiss has said he is willing to testify when appropriate.
Mr. Shapley described feeling stymied with the state of the investigation, and said his frustration crossed a “red line” when he heard Mr. Weiss say at a meeting that he was not, in fact, fully empowered to bring charges anywhere he wanted in the country, contradicting Mr. Garland’s public statements.
House Democrats attributed that allegation to a simple misunderstanding, but Mr. Shapley and Mr. Ziegler said it was more serious than that.
Mr. Shapley also singled out Lesley Wolf, a federal prosecutor in Delaware, for criticism. He said she blocked a search warrant at President Biden’s residence over concerns about “optics,” and said she halted questioning about the elder Biden.
Ms. Wolf “told investigators they should not ask about President Biden during witness interviews, even when the business communications of his son clearly reference him,” Mr. Shapley testified.
The U.S. attorney’s office in Delaware declined to comment.
Both of the I.R.S. investigators said they faced recriminations internally after coming forward with their whistle-blower disclosures.
“In coming forward, I believe I’m risking my career, my reputation and my case work outside of the investigation we are here to discuss,” said Mr. Ziegler, who described himself as a Democrat who is married to a man.
Several Democrats on the committee praised the witnesses and said they should be treated with respect. Mr. Raskin argued that Republicans have been throwing everything against the wall in an attempt to smear President Biden.
They have produced no proof that the president committed any crimes, and promoted one potential witness claiming to possess evidence of corruption by the Biden family — only to learn he was accused of brokering arms deals with China and Iran.
“We can conclude that this Inspector Clouseau-style quest for something that doesn’t exist has turned our committee into a theater of the absurd, an exercise in futility and embarrassment,” Mr. Raskin said.
Mr. Raskin also introduced into the record a letter from Lev Parnas, an associate of Rudolph W. Giuliani, who served as the personal lawyer to former President Donald J. Trump and who was tasked with digging up dirt on the Bidens in Ukraine.
“There has never been any factual evidence, only conspiracy theories spread by people who knew exactly what they were doing,” Mr. Parnas wrote to Mr. Comer. “With all due respect, Chairman Comer, the narrative you are seeking for this investigation has been proven false many times over, by a wide array of respected sources. There is simply no merit to investigating this matter any further.”
Glenn Thrush contributed reporting.