A defense attorney on Wednesday accused Vista-based prosecutors of repeatedly withholding evidence that could favor accused criminals ---- an action that could potentially jeopardize a defendant's right to a fair trial.

Defense attorney Kathleen Cannon, a senior member of the Vista branch of the public defender's office, argued to Superior Court Judge Harry Elias that there has been "a continuing pattern of failure" by prosecutors to supply evidence that could be important to the defense.

Cannon's statements came at the start of a hearing regarding fingerprint evidence in a low-level criminal case ---- the theft of two bicycles. Defense attorneys want the case dismissed, arguing that the prosecutor hadn't told them that a fingerprint on a pawn ticket was not clear enough to match to their client.

The larger question Cannon raised in court is the allegedly systemic problem of a failure to turn over evidence, which prosecutors are required to do.

"This is a problem, and that is the context in which this case is before you," Cannon told the judge, and cited two other recent instances of alleged failure to provide evidence.

Deputy District Attorney Kate Flaherty told Elias that "it was not appropriate or useful to go back in history, to cite other cases in other contexts."

The meat of Flaherty's arguments centered on the fingerprint case. She said the prosecutor in question, Deputy District Attorney Vanessa DuVall, had not violated any ethical obligations and had turned over the evidence.

Elias himself has emerged as a key figure in the battle. Prosecutors have accused Elias ---- a former prosecutor ---- of having bias against them.

Flaherty contended in court documents that highly critical, accusatory comments Elias made about the prosecutors' office reflect "a clear mind-set of bias and prejudice."

The heavyweight allegations drew a heavyweight audience in the courtroom Wednesday, including the top two supervisors of the Vista branch of the district attorney's office, and a chief administrator from the district attorney's headquarters in downtown San Diego.

Also on hand were Judge Joel Pressman, the supervising judge at the Vista courthouse; and William Trainor, the assistant supervisor of the public defender's office in Vista.

The allegations are a hot potato nobody wants to touch, and no one was willing to comment on whether failure to turn over evidence is a systemic problem. Trainor did say, though, that his office "stays on guard" for such issues to crop up.

District Attorney Bonnie Dumanis did not attend the hearing, but released a statement Wednesday afternoon saying that her office "takes our obligation to turn over evidence to the defense very seriously and we hold ourselves to the highest ethical standard, as was stated today in court."

On the surface, the bicycle theft case at the center of the battle is unremarkable. Experts matched six fingerprints to the defendant Kenneth Ray Bowles. But a seventh print was not clear enough to determine who it belonged to, and there was no mention of it in a report of the findings.

Technically, the battle is over the fingerprint. But the public defender's office used its complaint about fingerprint evidence in the theft case to highlight its claims of systemic problems.

In court, Cannon pointed to two other recent cases in which she said prosecutors violated the rules. In a gang rape case, the prosecutor did not give the victim's statements to defense attorneys. And in another case, the prosecution is alleged to have failed to turn over a bloody knife that could have worked in favor of the defense.

Neither of those cases went to trial; the defendants took plea deals offered by prosecutors. But the bicycle case did reach a jury, and Bowles was found guilty.

The fingerprint evidence became an issue after Bowles' jury trial.

When the allegations came up in Bowles' case late last year, Judge Elias put the prosecutor and others on the witness stand to testify about turning over the fingerprint evidence.

Prosecutors took exception to Elias' statements and actions during that hearing. Elias reportedly accused prosecutors of wrongdoing, including encouraging witnesses to give false testimony, and said the office has a bad reputation among judges in Vista.

In court documents, prosecutors called the hearing "a lynching" of the prosecutor who was under fire in the fingerprints case.

Call staff writer Teri Figueroa at 760-740-5442.