The special prosecutor who led a years-long investigation into Joe Biden’s son, Hunter, has criticised the president for making “baseless accusations” about the case and defended his investigation in a final report.

In the report, released Monday, David Weiss called his prosecution of the president’s son on gun and tax crimes “impartial” and “not partisan politics”.

Hunter Biden’s lawyer said the report showed Mr Weiss’s investigation “was a cautionary tale of the abuse of prosecutorial power.”

Biden issued an official pardon for his son, who was facing sentencing for two criminal cases, in early December.

While issuing the pardon, the president said his son had been “singled out” and called his cases “a miscarriage of justice” and “raw politics”.

Mr Weiss called those statements “gratuitous and wrong”.

“I prosecuted the two cases against [Hunter] Biden because he broke the law,” he wrote in his report.

Hunter Biden pleaded guilty to tax evasion charges earlier in September, and was found guilty of being an illegal drug user in possession of a gun in June.

His father’s full and unconditional pardon for his son came after the president had repeatedly said he would not give him clemency.

It was not the first time a US president has pardoned a family member.

Bill Clinton pardoned his younger half-brother, Roger Clinton, for a 1985 cocaine-related offence in 2001.

In 2020, Donald Trump pardoned Charles Kushner, the father-in-law of his daughter, Ivanka, who pled guilty to federal charges of tax evasion and illegal campaign donation payments in 2005.

In his report, Mr Weiss acknowledged that, but added: “none have taken the occasion as an opportunity to malign the public servants at the Department of Justice based solely on false accusations”.

Hunter Biden pleaded guilty to nine counts of federal tax fraud in September, for which he had been facing up to 17 years in prison.

He was also convicted of three felonies in connection with a gun purchase in June, for which he had been facing up to 25 years in prison.

The investigations into the president’s son had resurfaced uncomfortable and embarrassing details about his personal life, including his addiction to crack-cocaine and alleged payments to escorts.

President Biden had mostly kept quiet during the investigations into his son but came fiercely to his defence in his pardoning.

“There has been an effort to break Hunter – who has been five and a half years sober, even in the face of unrelenting attacks and selective prosecution,” President Biden said.

“In trying to break Hunter, they’ve tried to break me – and there’s no reason to believe it will stop here. Enough is enough.”

He added: “I hope Americans will understand why a father and a president would come to this decision.”

The pardon covers the period from 1 January 2014 to 1 December 2024, “including but not limited to” the tax and gun crimes for which he was found guilty.

Mr Weiss said due to that unconditional pardon, he could not make any “additional charging decisions” relating to Hunter Biden over that period.

“It would be inappropriate to discuss whether additional charges are warranted,” he said.

Mr Weiss has previously defended his inquiry into the president’s son.

In 2023, he told the House of Representatives Judiciary Committee there had never been political pressure or interference in his work from the justice department.

Mr Weiss’s investigation into Hunter Biden was heavily scrutinised on both sides of the political spectrum.

Democrats said it was politically charged and felt that Hunter Biden had an unfair target on his back.

Republicans believed the justice department was not pursuing charges aggressively enough and showing the president’s son unfair favouritism.

Hunter Biden’s guilty convictions came after a collapsed plea deal in 2023.

A judge declined to approve the deal – which Republicans had branded a “sweetheart deal” – that would have had Hunter Biden plead guilty to the tax evasion charges to avoid the more serious gun-related charges.

In a statement released Monday, Hunter Biden’s lawyer, Abbe Lowell, criticised Mr Weiss for the failed deal.

“Mr. Weiss also fails to explain why he reneged on his own agreement, a reversal that came at the 11th hour in court as he and his office faced blistering attacks from Republicans,” Mr Lowell said.