A judicial investigator has found evidence of “serious misconduct” in the prosecution of Ted Stevens on corruption charges, according to the federal judge who oversaw the corruption trial of former Alaska senator.

Stevens, an Alaska Republican, was found guilty by a jury in October 2008 of seven counts of making false statements on financial disclosure statements to hide about $250,000 in gifts and free renovations to his Alaska house.

Several months after Stevens’ conviction, the Justice Department discovered that prosecutors had failed to turn over notes that contradicted a witness and asked U.S. District Judge Emmet G. Sullivan to throw out the conviction.

Sullivan, who had reprimanded prosecutors several times during the lengthy trial for their handling of evidence and witnesses, erased the conviction, saying from the bench that “I have never seen anything approaching the mishandling and misconduct that I have seen in this case.”

The judge then ordered his own investigation of prosecutors by Henry F. Schuelke III, a D.C. defense attorney and former federal prosecutor. More than two years later, that investigation is complete, Sullivan said in an order posted on his docket Monday.

In the order, Sullivan wrote that Schuelke’s 500-page report said that the prosecution was “permeated by 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.”

The judge added that Schuelke and a colleague, William B. Shields, determined that “at least some of the concealment was willful and intentional, and related to many of the issues raised by the defense” during trial.

However, the judge wrote, the report recommended that the Justice Department attorneys not be prosecuted for criminal contempt. Schuelke came to this conclusion because the prosecutors did not “disobey an order that is sufficiently ‘clear and unequivocal’” to properly handle evidence, Sullivan wrote.

The judge did not indicate when he might issue a final ruling on whether the prosecutors should face criminal charges.

Though he scolded prosecutors several times during the trial, Sullivan never issued such an order. At one point during the trial, the exasperated judge said “I’m not going to write an order that says, ‘follow the law.’ We all know what the law is.”

Stevens, who lost his re-election bid shortly after being found guilty and whose charges were not dropped until April 2009, died in a small plane crash in Alaska in 2010. The report was submitted under seal. It will not be “made public at least until” it is reviewed by the Justice Department, attorneys for the prosecutors and Stevens’ lawyers, Sullivan wrote.