By Andrew Kreig posted by Michael Collins

Four days before Connecticut's Nora Dannehy was appointed to investigate the Bush administration's U.S. attorney firing scandal, a team of lawyers she led was found to have illegally suppressed evidence in a major political corruption case.

This previously unreported fact from Dannehy's past calls into question her entire national investigation. The revelation similarly compromises the pending investigation by her Connecticut colleague, John Durham, who since 2008 has been the nation's special prosecutor for DOJ and CIA decision-making involving torture.

Here's the story, which the Justice Integrity Project I lead just broke in Nieman Watchdog:

In September 2008, the Bush Justice Department appointed Connecticut career federal prosecutor Nora Dannehy to investigate allegations that Bush officials in 2006 illegally fired nine U.S. attorneys who wouldn't politicize official corruption investigations.

But just four days before her appointment, a federal appeals court had ruled that a team of prosecutors led by Dannehy illegally suppressed evidence in a major political corruption case in Connecticut. The prosecutors' misconduct was so serious that the court vacated seven of the eight convictions in the case.

The ruling didn't cite Dannehy by name, and although it was publicly reported it apparently never came up in the news coverage of her appointment.

But it now calls into question the integrity of her investigation by raising serious concerns about her credibility -- and about whether she was particularly vulnerable to political pressure from within the Justice Department.

Now, almost two years later, Dannehy has provided arguably the most important blanket exoneration for high-level U.S. criminal targets since President George H.W. Bush pardoned six Iran-Contra convicts post-election in late 1992.

The DOJ announced on July 21 that it has "closed the case" on the nine unprecedented mid-term firings because Dannehy found no criminal wrongdoing by DOJ or White House officials.

But the official description of her inquiry indicates that she either placed or acceded to constraints on the scope of her probe that restricted it to the firing of just one of the ousted U.S. attorneys, not the others -- and not to the conduct of the U.S. attorneys who weren't ousted because they met whatever tests DOJ and the White House created.

And although reaction to the closing of the inquiry has been muted, some observers are accusing her of a whitewash.

"This is an outrageous act of cowardice and cover-up!" former Alabama governor and alleged political prosecution victim Don Siegelman emailed me regarding DOJ's decision and the failure to interview him.

The Supreme Court vacated much of Siegelman's conviction last month after years of controversy, including charges by Republican whistleblowers that he was prosecuted primarily because he was a Democrat. As a result, House Judiciary Committee leaders and Siegelman's first trial judge, U.W. Clemon, last year separately urged Attorney Gen. Eric Holder to investigate suspected DOJ prosecution irregularities in what Clemon called "the most unfounded" prosecution he'd witnessed in nearly three decades on Alabama's federal bench.

Dannehy's probe, my reporting suggests, was compromised from the beginning.

She was appointed by Bush Attorney General Michael B. Mukasey on Sept. 29, 2008. On Sept. 25, the Second U.S. Circuit Court of Appeals in New York City found misconduct in a 2003 trial she had led.

The court found that the prosecution suppressed evidence that could have benefited the defendant, Connecticut businessman Charles B. Spadoni (pictured). Spadoni had been convicted of participating in a plot by his then-employer, Triumph Capital, Inc., to bribe former state Treasurer Paul Silvester to invest $200 million of state pension money with his firm.

But the appeals court found that prosecutors had failed to turn over to the defense an FBI agent's notes of a key interview they conducted with Silvester's attorney. In doing so, the court ruled, "the government deprived Spadoni of exculpatory evidence going to the core of its bribery case against him."

The court reversed Spadoni's convictions on seven counts of racketeering, racketeering conspiracy, bribery and wire fraud, leaving intact only an obstruction of justice conviction.

Prosecutors found by a court to have committed misconduct typically face some sort of internal investigation within the Justice Department. But whether there was any such investigation, and why or why not, is not publicly known.

As it happens, the Spadoni case also raises concerns relative to the ongoing federal probe of potential Bush administration wrongdoing in covering up torture that is being led by John H. Durham, another prosecutor from Connecticut. Durham supervised Dannehy's decade-long prosecution of Spadoni.

Like Dannehy, Durham was appointed by Mukasey in 2008 to be a special prosecutor with national responsibility. Durham's initial charge was to investigate suspected destruction of dozens of torture tapes by CIA personnel. In 2009, Holder expanded that probe to other decision-making, including by DOJ personnel.

Until now, neither DOJ nor anyone else has linked Dannehy and Durham by name to the prosecutorial misconduct against Spadoni, as far as I can determine. The court decision doesn't cite specific actions by the two. But it clearly refers to their case, and the information is readily available online in Lexis and in any good law library.

In April, as the acting U.S. Attorney for Connecticut, Durham signed a DOJ filing denying the merit of the appeals court finding of prosecution misconduct, while calling for Spadoni's continued prosecution for the remaining charge of obstruction of justice for deleting computer files in advance of a potential subpoena.

I sought additional comment beyond the court filings from Dannehy, Durham and Thomas Carson, DOJ's spokesman for its Connecticut office. Carson wrote me, "We have no further comment, as the matter is still pending."

The DOJ's letter said Dannehy found that the evidence "did not demonstrate any prosecutable criminal offense" in the 2006 firing of former New Mexico U.S. Attorney David Iglesias, and stated that there was no basis to broaden the investigation beyond his circumstances.

Iglesias, a Bush appointee whose 2008 book In Justice had a chapter entitled, "All Roads Lead to Rove," wrote me last year that he largely wants to put his ordeal behind him. Now returned to his original field of working in military justice, he told investigative reporter Jason Leopold:

I'm glad the matter is finally over. I'm gratified the Justice Department took the matter seriously enough to appoint an experienced corruption prosecutor to investigate. I will not second-guess her findings. I hope this scandal prevents future administrations and political leaders from attempting to politicize U.S. Attorneys.

House Judiciary Committee Chairman John Conyers issued this comment:

It is clear that Ms. Dannehy's determination is not an exoneration of Bush officials in the U.S. attorney matter as there is no dispute that these firings were totally improper and that misleading testimony was given to Congress in an effort to cover them up.

One such official, former attorney general Alberto Gonzales, who was forced out over the scandal, commented to CNN, "I feel angry that I had to go through this. That my family had to suffer through and what for?"

But several close observers of the case cried cover-up.