WASHINGTON (AP) – Pumping his fist in triumph, former Alaska Sen. Ted Stevens swapped places with his prosecutors Tuesday, his corruption conviction dismissed and his accusers suddenly facing criminal investigation themselves.

It was a stunning turnaround for one of the legendary fighters in Senate history, a man known for a temper that matched his Incredible Hulk neckties. Run out of office following the conviction last October, Stevens gave his long-awaited victory speech in court as a judge wiped away the verdict.

The prosecutors, who around this time would normally be arguing for Stevens’ prison sentence, were not in court. Kicked off the case following repeated accusations of withholding evidence, they’re now the subject of a criminal contempt probe.

“In nearly 25 years on the bench, I’ve never seen anything approaching the mishandling and misconduct that I’ve seen in this case,” U.S. District Judge Emmet Sullivan said before taking the extraordinary step of appointing a prosecutor to investigate the prosecution.

The unraveling of the case overshadowed the facts of a trial in which Stevens was shown to have accepted thousands of dollars in undisclosed gifts.

The case cost Stevens, 85, a Senate seat he had held for 40 years.

Now, the case could prove career-ending for prosecutors in the Justice Department’s public corruption unit.

“Until recently, my faith in the criminal system, particularly the judicial system, was unwavering,” Stevens told the court Tuesday, his first public comments since Attorney General Eric Holder announced he would drop the case. “But what some members of the prosecution team did nearly destroyed my faith. Their conduct had consequences for me that they will never realize and can never be reversed.”

Sullivan appointed Washington attorney Henry Schuelke to investigate possible contempt and obstruction by the Justice Department team. Schuelke is a former prosecutor and veteran defense attorney who oversaw a Senate Ethics Committee investigation into influence-peddling allegations against former New York Sen. Alfonse D’Amato in 1989.

Sullivan said the misconduct was too serious to be left to an internal probe by the Justice Department, which he said dragged its feet before investigating. He criticized former Attorney General Michael Mukasey for not responding to complaints: “Shocking, but not surprising,” Sullivan said.

He worried aloud about how often prosecutors withhold evidence, from Guantanamo Bay terrorism cases to public corruption trials. He called on Holder to retrain all prosecutors in the department.

The decision to open a criminal case raises the question of whether the prosecutors, who include top officials in the department’s public corruption unit, can remain on the job. The investigation carries the threat of prison time, fines and disbarment.

It also threatens to derail the investigation into other public officials, including Rep. Don Young, R-Alaska, who has been under scrutiny by the same prosecutors now being investigated. Young’s lawyer attended Tuesday’s hearing but said nothing after it ended.

Subjects of the criminal probe are lead prosecutor Brenda Morris, the department’s No. 2 corruption official and an instructor within the department; public Integrity prosecutors Nicholas Marsh and Edward Sullivan; Alaska federal prosecutors Joseph Bottini and James Goeke and William Welch, who did not participate in the trial but who supervises the Public Integrity section and has overseen every major public corruption case in recent years.

After the trial verdict, an FBI whistleblower accused the team of misconduct and Sullivan held prosecutors in contempt for ignoring a court order.

The prosecution team was replaced and, last week, the new team acknowledged that key evidence had been withheld. That included notes from an interview with the government’s star witness, contractor Bill Allen.

On the witness stand, Allen said a mutual friend told him not to expect payment for Stevens’ home renovations because the senator only wanted the bill to protect himself. It was damaging testimony that made Stevens look like a scheming politician trying to conceal his freebies.

But in the previously undisclosed interview by prosecutors, Allen had no recollection of such a discussion. And he valued the renovation work at far less than what prosecutors alleged at the trial.

“I was sick in my stomach,” attorney Brendan Sullivan said Tuesday, recalling seeing the new evidence for the first time. “How could they do this? How could they abandon their responsibilities? How could they take on a very decent man, Ted Stevens, who happened to be a United States senator, and do this?”

The Justice Department did not comment after court, and the prosecutors under investigation either declined comment or did not respond to messages. But Paul O’Brien, a federal prosecutor newly assigned to the case, apologized to the judge on behalf of the department.

Despite the prosecutorial misconduct, the trial revealed that Stevens – regardless of Allen’s discredited testimony – accepted a massage chair, a stained-glass window and an expensive sculpture and never disclosed them on Senate documents.

None of that mattered Tuesday as Stevens stood at the courtroom lectern. Wearing a pin of the U.S. and Alaska flags on his sweater, he recounted his career in government – from flying planes in World War II to serving as U.S. attorney to his storied decades in the Senate.

He thanked his friends, his supporters and his wife. And he vowed to push his former Senate colleagues for tough new laws on prosecutorial misconduct.

Then, with the prosecution team feeling the scrutiny that Stevens felt for years, he smiled, posed for pictures with his family outside the courthouse and said:

“I’m going to enjoy this wonderful day.”

AP-ES-04-07-09 1652EDT