In a sentencing memo filed Friday, lawyers representing Paul Manafort, the former chairman of President Donald Trump's campaign, accused the special counsel Robert Mueller of "spreading misinformation" to "vilify" Manafort.

They added that Mueller's team is trying to "impugn his character in a manner that this country has not seen in decades."

Manafort's team argued that he should get a drastically reduced prison sentence given the nature of the crimes Manafort pleaded guilty to, and the fact that he is a first-time offender.

In a sentencing memo Paul Manafort’s lawyers submitted on his behalf Friday, they argued that the crimes Manafort has been convicted of warrant a prison sentence that is “substantially below the range” the special counsel Robert Mueller’s team suggested.

Manafort’s lawyers argued in their sentencing memo Friday that the former chairman of President Donald Trump’s campaign should get a far lighter sentence than what Mueller recommended given that he is “a first-time offender and given the nature of the offenses for which” he was convicted.

They noted that in addition to accepting responsibility for two counts of obstruction and conspiracy, Manafort "admitted his guilt with respect to the conduct involved in the remaining charges in this case."

"Mr. Manafort agreed to cooperate with [Mueller] and ... met with attorneys and investigators from the government numerous times," they added. "He also testified before a grand jury" in Washington, DC, on two occasions, they wrote.

Manafort was convicted last year on eight counts of tax fraud, bank fraud, and failure to report foreign bank accounts. He was set to face a second trial for additional charges of money laundering, false statements, and illegal foreign lobbying, but Manafort struck a plea deal with Mueller’s office instead, ultimately pleading guilty to conspiracy and obstruction.

Read more: Mueller called Manafort a 'hardened' criminal who 'repeatedly and brazenly violated the law' in a harsh sentencing memo

But after Manafort agreed to cooperate, prosecutors learned that he had lied to them about several interactions and events that are under scrutiny in the Russia investigation. They were also angered when they found out that Manafort's lawyers were briefing Trump's legal team on everything he was being questioned about. The conduct was unusual, given that Trump is a subject of interest in the Russia investigation.

Last month, a federal judge nullified Manafort's plea deal after ruling that he lied to prosecutors in three out of five disputed instances Mueller's office outlined.

Afterward, Mueller’s team filed a sentencing memo in which they did not make a specific sentencing recommendation, as has been their practice so far, but noted that federal sentencing guidelines call for a prison term of 19 to 24.5 years. They urged the court to “take into account the gravity of [Manafort’s] conduct, and serve both to specifically deter Manafort and generally deter those who would commit a similar series of crimes.”

In their sentencing memo on his behalf Friday, Manafort's lawyer accused Mueller's team of trying to "vilify" their client, adding that prosecutors' conduct was "beyond the pale and grossly overstates the facts before this Court."

"The Special Counsel’s conduct comes as no surprise, and falls within the government’s pattern of spreading

misinformation about Mr. Manafort to impugn his character in a manner that this country has not

experienced in decades," Manafort's lawyers wrote.

To support their claims, the former Trump campaign chairman's lawyers referenced the Justice Department inspector general's report in June 2018 into the FBI's and Justice Department's handling of investigations into Trump and Hillary Clinton leading up to the 2016 election.

The report concluded that although FBI officials' conduct during both investigations was inappropriate, there was no "documentary or testimonial evidence that improper considerations, including political bias, directly affected the specific investigative actions we reviewed."

Manafort's lawyers also pointed to the Justice Department's recent charges against a senior Treasury Department official who is accused of leaking information concerning suspicious activity reports (SARs) related to Manafort and Michael Cohen to the media.

Neither the charges nor the inspector general's report made any allegations that government officials "spread misinformation," as Manafort's lawyers claimed in their sentencing memo.

The sentencing memo went on to highlight that federal sentencing "guidelines are guidelines — that is, they are truly advisory."