Former Special Counsel Robert Mueller on Saturday vigorously defended his team's decision to prosecute Roger Stone, stopping short of directly attacking President Trump, who commuted Stone's sentence the day prior.

"Stone was prosecuted and convicted because he committed federal crimes. He remains a convicted felon, and rightly so," Mueller said in an op-ed published by The Washington Post.

His op-ed defends both the decision to prosecute Stone, as well as the overarching investigation that Republicans and the president have repeatedly denounced. Mueller said he felt "compelled to respond both to broad claims that our investigation was illegitimate and our motives were improper."

"The Russia investigation was of paramount importance," he added. He went on to indirectly address Republicans' accusations that the investigation was led by crooked actors within the Justice Department (DOJ). "The women and men who conducted these investigations and prosecutions acted with the highest integrity. Claims to the contrary are false," he said.

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Saturday's op-ed represents perhaps the boldest statement from Mueller, who was criticized for offering what was considered a tepid testimony to House investigators last year. Former FBI Director James Comey similarly defended the investigation last May and ridiculed accusations that the DOJ engaged in a "deep state" conspiracy against Trump.

On Friday, White House Press Secretary Kayleigh McEnany ripped into Mueller's team, describing the Russia investigation as a witch hunt and Stone the victim of a "hoax."

"As it became clear that these witch hunts would never bear fruit, the Special Counsel’s Office resorted to process-based charges leveled at high-profile people in an attempt to manufacture the false impression of criminality lurking below the surface," McEnany said.

"These charges were the product of recklessness borne of frustration and malice. This is why the out-of-control Mueller prosecutors, desperate for splashy headlines to compensate for a failed investigation, set their sights on Mr. Stone."

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She added that "Mr. Stone was charged by the same prosecutors from the Mueller Investigation tasked with finding evidence of collusion with Russia.  Because no such evidence exists, however, they could not charge him for any collusion-related crime.  Instead, they charged him for his conduct during their investigation. The simple fact is that if the Special Counsel had not been pursuing an absolutely baseless investigation, Mr. Stone would not be facing time in prison."

Stone was ultimately convicted in November 2019 on seven counts of witness tampering, obstruction and making false statements to Congress. Trump's commutation came just days before the 67-year-old political operative was set to serve 40 months in prison.

Mueller acknowledges in the op-ed what he said in last year's report -- that his team was unable to establish a conspiracy between the Trump campaign and Russia.

He added: "The investigation did, however, establish that the Russian government perceived it would benefit from a Trump presidency and worked to secure that outcome. It also established that the campaign expected it would benefit electorally from information stolen and released through Russian efforts."

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Mueller specifically identified Stone as one of the "numerous links" between the campaign and Russia. He added that Stone "communicated in 2016 with individuals known to us to be Russian intelligence officers, and he claimed advance knowledge of WikiLeaks’ release of emails stolen by those Russian intelligence officers."

"Robert Mueller and his corrupt investigation failed to hold anyone in the Obama-Biden Administration accountable for their negligence toward Russian interference or for spying on the Trump Campaign based on a Democrat-funded dossier full of lies, and instead wasted taxpayer dollars trying to undo an election. Mr. Mueller should keep his promise to the American people and let the report, which fully exonerated the President, stand instead of pontificating in the editorial pages with more spin," Judd Deere, Special Assistant to the President and Deputy Press Secretary, told Fox News on Saturday night.