WASHINGTON — Federal prosecutors handling the 2008 ethics trial of the late Sen. Ted Stevens of Alaska “never conducted or supervised a comprehensive and effective review for exculpatory information,” a court-appointed investigator found in a blistering 514-page report released Thursday.

“The investigation and prosecution of U.S. Senator Ted Stevens were permeated by the systematic concealment of significant exculpatory evidence which would have independently corroborated Senator Stevens’s defense and his testimony, and seriously damaged the testimony and credibility of the government’s key witness,” wrote Henry Schuelke, the investigator assigned to the case.

The basic findings of Schuelke’s report, released by Judge Emmet Sullivan, the federal judge overseeing the case, had been known since November. But the full report provides the most detailed look yet at the inner workings of the prosecution of Stevens, a long-serving Republican senator, as well as a series of failures by prosecutors to live up to their obligation to turn over to the defense information that could have resulted in Stevens’ acquittal.

Stevens, who died in a plane crash in 2010, was convicted of failing to disclose gifts and services from an oil services executive. Days after the conviction, he narrowly lost his bid for a seventh Senate term to his Democratic opponent. In early 2009, the then-new attorney general, Eric Holder, asked the judge to set aside that conviction because of the discovery that prosecutors had failed to turn over potentially exculpatory evidence.