THEY have been identified in sworn testimony as taking part in the 2009 beating that ended in the death of Philadelphia Phillies fan David W. Sale Jr.

But after a mistrial was declared on Tuesday in the murder trial of Francis Kirchner, Charles Bowers and James Groves, the question confronting a Philadelphia judge is whether the trio should go free because of what one defence attorney called "prosecutorial misconduct".

Common Pleas Court Judge Shelley Robins New declared the mistrial after four days of testimony, when a friend of the victim unexpectedly identified Mr Kirchner, 30, as the man who made the fatal kick to Mr Sale's head in the July 25, 2009, melee.

Judge New said the surprise identification by Ryan Tulino violated the court rule obligating a prosecutor to disclose to defence lawyers in advance incriminating evidence, including identification testimony.

New said Mr Tulino's "blurt-out" on Monday was also unfair to Assistant District Attorney Richard Sax. To counter defence claims of prosecutorial misconduct, she said, Mr Sax would have to testify and attack his own witness' credibility.

The judge scheduled a hearing for Wednesday to see when - or whether - the case might be retried.

Although Judge New had said she would rule on Tuesday on the defence mistrial motion, that did not dilute the emotional impact on families of the victim or defendants.

Mr Sale's mother, Laverne Sale Young - whose son has been portrayed by the defence as equally intoxicated and aggressive in the brawl between a suburban bachelor party and a group from a tavern in Philadelphia's Fishtown neighborhood - left court before the ruling and fainted in an anteroom. Paramedics were called. Mrs Young's husband, Michael, said she was OK.

At issue tomorrow for Judge New is whether Mr Tulino's words were erroneous or spontaneous, or prosecutorial misconduct that should bar a new trial.

Mr Kirchner's attorney, Jack McMahon, said he would ask to bar a retrial under the constitutional provision against double jeopardy - trial twice for the same crime.

Mr McMahon said that if prosecutorial misconduct is established, a judge may bar retrial on the grounds that the defendant could not be fairly tried.

"A trial is supposed to be fair, with full disclosure," Mr McMahon said afterwards. "It's not supposed to be sneaky. That's what we all deserve, but that's not what happened in this case."

Sax said he was "very disappointed. We have respect for the court, but we do not in any shape or form agree with this decision".

Mr Sax said he did not hide identification testimony from the defence. Mr Tulino had never before identified Mr Kirchner and Mr Sax said he did not ask Mr Tulino whether he could identify any of the three. The identification was elicited in cross-examination by Brian J. McMonagle, who represents Mr Bowers, Mr Sax said.

Much of Judge New's analysis of Mr McMahon's motion to bar retrial may focus on a closed-door conference between judge and lawyers before court started on Monday.

Defence lawyers said Mr Sax told them Mr Tulino was not an identification witness. Mr Sax said afterwardd that Mr Tulino approached him before going on the witness stand with a "rhetorical question: 'What would happen if I told you I recognised someone?"'

Mr Sax said he told Mr Tulino that "identification is not an issue in this trial" but that his responsibility was, "Tell the truth."

It was the second surprise identification by a prosecution witness. On Friday, Mr Sale's friend Daniel Curran identified Mr Kirchner as the man who kicked Mr Sale in the head. Mr McMahon then moved for a mistrial, which Judge New denied.

Although he called the surprise identifications misconduct, Mr McMahon stopped short of accusing Mr Sax of purposely misleading him.

"That's for Richard Sax to say," said Mr McMahon. "That's not what I'm about. I'm here to defend Frankie Kirchner."

Besides Mr Kirchner, the defendants are Mr Bowers, 37, and Mr Groves, 48. They were part of a group bused to the game that day from Moe's Tavern, a Fishtown pub.

Mr McMonagle declined to comment about whether he would join Mr McMahon's motion. Mr Groves' attorney, Scott DiClaudio, praised the mistrial ruling:

"After two days, not one witness has said my client was there at the time of the fatal kick," he said

Although lawyers for Mr Bowers and Mr Groves have acknowledged that their clients hit Mr Sale during the fistfight, Mr McMahon has said that Mr Kirchner never touched Mr Sale and was fighting elsewhere in the carpark.

Mr Kirchner has the most to lose. He alone is charged with first-degree murder and faces life in prison without parole if found guilty. Mr Bowers and Mr Groves are charged with third-degree murder, which carries 20 to 40 years in prison.

Mr Kirchner remains in custody without bail, as with all first-degree murder defendants. Mr Bowers and Mr Groves are free after posting bail.