An investigation into the bungled prosecution of former Sen. Ted Stevens (R-Alaska) found that while Justice Department attorneys concealed evidence that would have exonerated the late Senator, they should not be prosecuted for the “significant, widespread, and at times intentional misconduct” that derailed the government’s case, a federal judge said today.

The conclusions of the investigation, which began in April 2009, were referenced in an order issued by U.S. District Court for the District of Columbia Judge Emmet G. Sullivan, who presided over Stevens’ corruption trial in the fall of 2008.

Though Stevens was indicted, tried and found guilty of making false statements on his annual financial disclosure forms filed with the Senate because he did not disclose gifts he received, the verdict was vacated after the Department of Justice concluded its prosecutors had failed to hand over evidence that would have bolstered Stevens’ defense.

Stevens died in August 2010 when the private plane in which he was traveling crashed in rural Alaska.

Sullivan appointed Washington, D.C., attorney Henry F. Schuelke of the law firm Janis, Schuelke & Wechsler to investigate and possibly prosecute the six attorneys in the Justice Department’s Public Integrity Section who were responsible for the botched Stevens prosecution at the time the government first admitted wrongdoing.

“The prosecutorial misconduct … permeated the proceedings before this Court to a degree and extent that this Court had not seen in twenty-five years on the bench,” Sullivan wrote of his decision to bring on Schuelke in his order.

Schuelke, in a 500-page report that resulted from the review of 150,000 pages of documents and the deposition of 12 witnesses, found that the Stevens case was “permeated by the systematic concealment of significant exculpatory evidence which would have independently corroborated his defense and his testimony, and seriously damaged the testimony and credibility of the government’s key witness,” Sullivan quoted.

However because the court did not give the attorneys a direct order to comply with their legal obligation to turn over the evidence, they should not be prosecuted for misconduct, Schuelke concluded.

“Because the Court accepted the prosecutors’ repeated assertions that they were complying with their obligations and proceeding in good faith, the court did not issue a ‘clear and unequivocable’ order directing the attorneys to follow the law,” Sullivan wrote.

Copies of Schuelke’s report, which remains under seal, were given to the Justice Department and the late Senator’s attorneys for review. They have until Dec. 5 to object to its contents being made public.

One of the prosecutors in the Stevens case, Nicholas Marsh, committed suicide last fall, and his lawyer said at the time that Marsh was distraught about the effect the Stevens case might have on his career.