WASHINGTON — A pair of career IRS agents told the House Oversight Committee on Wednesday that the Justice Department stifled their investigation into tax crimes by the son of US president Joe Biden and pursued weaker charges than they had recommended.

But some Republicans did not want to delve into the whistleblower allegations, including Representative Marjorie Taylor Greene, who used her question time during the hearing to display what appeared to be naked pictures of Hunter Biden obtained from his laptop.

“What’s even more troubling to me is that the Department of Justice has brought no charges against Hunter Biden that will vindicate the rights of these women,” Greene said, holding up pictures that appeared to show the president’s son making sex tapes with women whom Greene claimed were sex workers.

“Should we be displaying this, Mr. Chairman?” the committee’s top Democrat Representative Jamie Raskin asked committee Republican chair James Comer, who did not answer.

Naked pictures of Hunter Biden are exactly the sort of sordid material that Comer once said he considered “very counter to a credible investigation”.

Comer had called the hearing to hear from IRS whistleblowers who have claimed the Justice Department prevented them from taking investigatory steps they thought were warranted to bring charges against the president’s son.

The younger Biden has been open about his addictions to drugs and alcohol spiralling out of control following his brother’s death in 2015. He made questionable business deals with foreign nationals that earned him millions and created an appearance of conflict of interest because of his father’s government service. He’s due in court next week on misdemeanour charges relating to his alleged failure to pay tax on income he earned in 2017 and 2018.

The IRS whistleblowers said they recommended he be charged with felonies, but their recommendations were rebuffed by Justice Department officials in an unusual manner. And they said the federal prosecutor overseeing the case, US Attorney David Weiss, a holdover from the Donald Trump administration, told them he couldn’t bring charges outside of Delaware. Weiss and US Attorney General Merrick Garland have insisted Weiss had complete authority to bring charges however he wanted.

The hearing did not resolve the contradiction between the IRS agents’ previous allegations and the denials from the Justice Department. In their public testimony, the agents essentially repeated what they’d already told lawmakers in a private deposition.

“It appeared to me, based on what I experienced, that the US attorney in Delaware, in our investigation, was constantly hamstrung, limited and marginalised by DOJ officials as well as other US attorneys,” IRS special agent Joseph Ziegler told the House Oversight Committee.

The other whistleblower, Gary Shapley, a supervisory agent in the IRS criminal division, said he didn’t know if Garland had deliberately lied.

“I have never claimed to have evidence that Attorney General Garland knowingly lied to Congress,” Shapley said.

House Speaker Kevin McCarthy has said Republicans would move to impeach Garland if the whistleblower testimony proves true. “We need to get to the facts, and that includes reconciling these clear disparities,” McCarthy said in June.

The allegation that the Justice Department went easy on a member of the president’s family has become a centrepiece of an overarching Republican message that there’s a two-tier justice system persecuting Trump and his supporters and protecting the Bidens. The former president has been indicted on federal charges related to retaining classified public documents and he could face additional charges for his efforts to undo the 2020 election.

Democrats suggested the discrepancy between statements from the Justice Department and the whistleblowers reflected their frustration with the common phenomenon of prosecutors not following through on investigators’ recommendations.

“I think you have a tough view on what you think the law should be. This is why we have a prosecutorial system,” Democrat Representative Ro Khanna said. “It turns out, often your recommendations on who should be charged differ from some of the other folks, and that’s what happened in this case.”

Shapley testified that such disagreements occur in “the vast majority” of cases but insisted the Hunter Biden case was different from any other he’d worked on.

Raskin said it appeared Hunter Biden had not received any favouritism.

“The fact that Hunter Biden faced a four-year criminal probe involving dozens of agents and prosecutors from the IRS, the FBI, the US attorney’s office in Delaware,” Raskin said, “demonstrates in my mind at least that he received no special treatment, but arguably tougher treatment than the millions of people who never faced criminal investigation for doing the same thing.”