An attorney for a former congressman convicted on several federal charges is requesting that the Department of Justice (DOJ) launch an investigation into his case, alleging improper conduct during the course of the probe.

Former Rep. Rick Renzi (R-Ariz.) was convicted in 2013 over an illegal federal land swap. He served 3 years in federal prison after being found guilty on 17 of the 32 federal counts he was indicted on, including racketeering, extortion, bribery and money laundering.

ADVERTISEMENT But an attorney for Renzi, Kelly Kramer, alleged in a letter sent to the DOJ on Wednesday and obtained by The Hill that improper conduct on the part of the Justice Department led to an unfair investigation and prosecution of the former congressman.

“In my view, the government’s misconduct not only deprived Mr. Renzi of his constitutional right to a fair trial, but it allowed the jury to convict an innocent man,” Kramer wrote.

A Justice Department spokesperson did not immediately return a request for comment from The Hill on Wednesday.

The letter from Renzi's attorney alleges that the DOJ “recorded dozens of attorney-client privileged calls” during the course of a wiretap, and “denied all wrongdoing” when Renzi raised concerns about the recordings. A court did not allow the wiretap to be used during Renzi’s trial.

Kramer also claims that a special agent of the FBI interviewed a witness in the case who said he had learned of a farm involved in the case from a source other than Renzi.

The letter states that the evidence, which could have helped Renzi’s case, was included in the agent’s notes but left out of the FBI report about the witness interview.

“Critically, the report of interview was provided to the defense, but the agents’ notes were not revealed until after Mr. Renzi reported to prison,” the letter reads.

The document states that the witness also testified before a grand jury and during Renzi’s trial that he had only heard about the farm from Renzi.

Kramer asserts that "the government sponsored this false claim, both at trial and in the grand jury, while concealing" the witness's initial statement.

The attorney wrote that federal courts "have reviewed some of the misconduct discussed herein, but because much of it was concealed until after Mr. Renzi’s direct appeal, they have never had the opportunity to consider the cumulative impact of the misconduct, which I believe to have been substantial."

"On behalf of Mr. Renzi, I respectfully request that you conduct a full and fair investigation.”