Senate Minority Leader Mitch McConnell issued a scathing letter Tuesday accusing the Justice Department of taking a "startling turn for the worse" under the Biden administration and injecting left-wing political bias into its treatment of violent criminals.

In a letter to the DOJ and Andrew Luger, President Biden's nominee for Minnesota's highest-ranking federal prosecutor, McConnell, R-Ky., blasted the U.S. Attorney’s Office for seeking reduced sentences for rioters arrested during the 2020 George Floyd protests. One such person was Montez Terriel Lee Jr., who was convicted of the arson of a pawn shop that resulted in the death of a man. Lee was sentenced to 10 years in prison.

SEN. HAWLEY ACCUSES DOJ OF 'FAR-LEFT POLITICKING' BY ASKING FOR REDDUCED SENTENCE FOR VIOLENT RIOTER

Senate Minority Leader Mitch McConnell

Senate Minority Leader Mitch McConnell walks to the Senate floor at the U.S. Capitol on Jan. 18, 2022. (Eric Lee/Bloomberg via Getty Images)

"Political violence is a cancer in free societies," McConnell wrote. "To use a parallel example, it would seem almost insane to argue that a criminal who assaulted the United States Capitol on January 6th, 2021, with the explicit intention of obstructing Congress’ constitutional duties, should receive a lesser sentence than somebody else who trespassed on federal property at a different time just because he could. 

"But in the case of Mr. Lee, the acting U.S. attorney in Minnesota seems to have reached the bizarre conclusion that his radical political motives somehow excuse, rather than exacerbate, his wrongdoing," he continued. "It is critically important for lawful authority to deter those who would intimidate their political opponents through violence or its threats. It is therefore shocking that the former acting U.S. attorney in Minnesota saw things differently, presumably because he bears some sympathy for the cause Mr. Lee violently supported. That is unacceptable."

Sen. Tom Cotton, R-Ark., issued a similar letter Tuesday to U.S. Attorney General Merrick Garland demanding answers on Lee's prosecution.

"Showing leniency toward a career criminal who committed murder is bad enough," Cotton wrote. "But justifying the murder because the career criminal shares the Biden administration’s politics is beyond the pale. The American people deserve to know whether leniency for left-wing murderers is the official policy of the Biden Department of Justice, or whether this travesty was a one-off…"

Tom Cotton

Sen. Tom Cotton speaks during a Senate Armed Services Committee hearing on Capitol Hill on Sept. 28, 2021.  (Patrick Semansky)

Sen. Josh Hawley, R-Mo., sent a similar letter to Garland last week, noting that the DOJ said in a court filing before Lee's sentencing that the violent protests were a way for men and women to express themselves.

"There appear … to have been many people who felt angry, frustrated and disenfranchised, and who were attempting, in many cases in an unacceptably reckless and dangerous manner, to give voice to those feelings. Mr. Lee appears to be squarely in this latter category," the DOJ's filing stated. "And even the great American advocate for nonviolence and social justice, Dr. Martin Luther King Jr., stated in an interview with CBS’ Mike Wallace in 1966 that ‘we’ve got to see that a riot is the language of the unheard.’

"In light of these circumstances, the analysis of the [sentencing] guidelines does not appear appropriate," DOJ concluded. The department asked for a "downward variance" of 12 years for Lee, much lower than the sentencing guidelines of up to 20 years.

Josh Hawley

Sen. Josh Hawley makes a point during a Senate Judiciary Committee hearing on Capitol Hill on Sept. 29, 2021. (Tom Williams-Pool/Getty Images)

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Hawley said the DOJ’s findings make it evident that "the toxic ideology of critical race theory has spread through the Department."

"While you treat persons charged with petty offenses from the January 6 riot as hardened criminals, now even the most heinous offenses can be treated leniently, as long as the perpetrator is of the correct race and the crime can be connected to some progressive cause célèbre," the senator wrote.

The DOJ did not immediately respond to Fox News Digital's request for comment.

Fox News’ Timothy Nerozzi and Kelly Laco contributed reporting.