"T$3 his appears from all external circumstances to be an instance of President Trump and Attorney General Barr acting in concert to protect Stone from punishment", the letter stated.
Stone is a flamboyant political operative - a self-described "dirty trickster" - who was convicted past year of lying to Congress, witness tampering and obstructing a congressional investigation into Russian meddling in the 2016 election.
The House Judiciary Committee will grill Mr. Barr about his role in the Stone case March 31.
After chastising the prosecutors and judge in the trial of his longtime adviser Roger Stone, President Donald Trump on Thursday criticized the jury that convicted the veteran Republican operative, raising further concerns about political interference in the US judicial system. On Monday, the DOJ released a sentencing memo that recommended seven to nine years in federal prison for Stone. Shortly thereafter, the Justice Department signaled that it would seek a more lenient sentence for Stone, a move that prompted all four career prosecutors to withdraw from the case - and one to resign from the government.
The removal of former US attorney for D.C. Jessie Liu, who oversaw the prosecutions of Trump associates Roger Stone, Michael Flynn and Paul Manafort.
Stone was convicted in November of a seven-count indictment that accused him of lying to Congress, tampering with a witness and obstructing the House investigation into whether the Trump campaign coordinated with Russian Federation to tip the 2016 election.
Two of the attorneys had worked under former special counsel Robert Mueller, while the other two had picked up the case when it was transferred to the DC US attorney's office.
Aaron Zelinsky, Jonathan Kravis, Adam Jed and Michael Marando quit the case while Democrats demanded an independent investigation into what they described as a dangerously politicised and corrupt justice department. Stone's crimes and said it would file a new sentencing memo. This turn has come within a week of the Senate GOP refusing to hold Trump accountable for his impeachable offenses. "Please take just a few seconds to help by signing the petition to pardon Roger Stone!" says the committee's website.
Meanwhile, according to federal election data, another juror in the Stone trial, Seth Collins, had previously donated to former Democratic presidential candidate Beto O'Rourke and other left-wing causes. "He claims an absolute right to order the Justice Department to do whatever he wants".
Congratulations to Attorney General Bill Barr for taking charge of a case that was totally out of control and perhaps should not have even been brought. He later told reporters he didn't speak to Justice Department officials, though he said he could if he wanted.