It sounds like the decision to drop the charges against Ted Stevens was prompted by a new example of prosecutorial misconduct, which only came to light recently.

Here's the key excerpt from the Justice Department's motion:

The Government recently discovered that a witness interview of Bill Allen took place on April 15, 2008. While no memorandum of interview or agent notes exist for this interview, notes taken by two prosecutors who participated in the April 15 interview reflect that Bill Allen was asked about a note dated October 6, 2002, that was sent from the defendant to Bill Allen. The note was introduced at trial as Government Exhibit 495 and was referred to as the "Torricelli note." The notes of the April 15 interview indicate that Bill Allen said, among other things, in substance and in part, that he (Bill Allen) did not recall talking to Bob Persons regarding giving a bill to the defendant. This statement by Allen during the April 15 interview was inconsistent with Allen's recollection at trial, where he described a conversation with Persons about the Torricelli note. In addition, the April 15 interview notes indicate that Allen estimated that if his workers had performed efficiently, the fair market value of the work his corporation performed on defendant's Girdwood chalet would have been $80,000. Upon the discovery of the interview notes last week, the Government immediately provided a copy to defense counsel.

Defendant Stevens was not informed prior to or during trial of the statements by Bill Allen on April 15, 2008. This information could have been used by the defendant to cross- examine Bill Allen and in arguments to the jury. The Government also acknowledges that the Government's Opposition to Defendant's Motion for a New Trial provided an account of the Government's interviews of Bill Allen that is inaccurate.

In other words, prosecutors didn't share with Stevens defense key evidence suggesting that Allen --by far the most important witness for the prosecution in the case -- said contradictory things in an interview with prosecutors and on the stand. That could obviously have reduced his credibility as a witness, had the defense team been able to make an issue out of it.

But this mistake by the Feds comes on the heels of a string of other well-documented errors and mishaps.

Even before Stevens, the former Alaska GOP senator, was found guilty in late October of concealing gifts from Allen on his Senate disclosure form, prosecutors were reprimanded by the judge for not turning over key evidence to the defense.

Then there was confusion last November about whether another government witness had been granted an immunity deal in exchange for his testimony. The witness claimed the government had gone back on the deal, a charge prosecutors denied.

The following month, a complaint surfaced from an FBI whistleblower, alleging that the government "schemed to relocate a witness," that an employee working on the investigation accepted artwork and employment for a relative from a cooperating source, that another FBI agent had an improper personal relationship with Allen, and that this information was concealed from the defense.

In late January, the lead prosecutor on the case, William Welch, who ran DOJ's Public Integrity Section, admitted to the judge that he had erred when he said that the government employees cited in the publicly filed whistle-blower complaint wanted their story to be made public. In fact, Welch now acknowledged, not all the government employees wanted their stories made public.

Later that month, the judge ruled that Welch and three other prosecutors were in contempt of court, for failing to turn over documents related to the whistleblower allegations, after being ordered by the judge to do so.

And soon afterwards, the Justice Department replaced Welch and his team with new prosecutors.

And now, the new case of withholding of evidence, resulting in the charges being dropped.

As a result, the crown jewel conviction of the wide-ranging, years long probe of corruption in Alaska politics is destroyed. A fitting testament, perhaps, to the Bush Justice Department's record of failure.