(CNN)A deputy to former special counsel Robert Mueller plans to tell a congressional panel Wednesday that the “highest levels” of the Justice Department politicized the sentencing of President Donald Trump’s longtime friend and adviser Roger Stone by pressuring the acting US attorney for the District of Columbia to ease up on his sentencing, according to written testimony the committee released Tuesday.

Aaron Zelinsky, a member of Mueller’s team who prosecuted the Stone case, submitted testimony that Stone was “being treated differently from any other defendant because of his relationship to the President.”

“What I saw was the Department of Justice exerting significant pressure on the line prosecutors in the case to obscure the correct Sentencing Guidelines calculation to which Roger Stone was subject — and to water down and in some cases outright distort the events that transpired in his trial and the criminal conduct that gave rise to his conviction,” Zelinsky said in his written statement.

“I was told that the Acting US Attorney for the District of Columbia, Timothy Shea, was receiving heavy pressure from the highest levels of the Department of Justice to cut Stone a break, and that the US Attorney’s sentencing instructions to us were based on political considerations,” Zelinsky wrote. “I was also told that the acting US Attorney was giving Stone such unprecedentedly favorable treatment because he was ‘afraid of the President.'”

Zelinsky resigned from the case this year after Shea proposed a lighter sentencing than the prosecutors had sought. Zelinsky is testifying alongside John Elias, a career official in the Justice Department’s Antitrust Division, about the politicization of the Justice Department under Attorney General William Barr. Elias is testifying about the decision to investigate California’s air quality emissions standards following Trump’s tweets on the issue last year.