A state judge heard testimony Monday from a prosecution weapons expert during a hearing to determine whether manslaughter charges should be dismissed against retired NBA (search) star Jayson Williams (search).

The hearing, held in the jury's absence, centered on whether the prosecution intentionally withheld notes and photographs the expert took when he examined the shotgun that Williams was handling when the weapon fired, killing a hired driver two years ago.

Testimony from Larry Nelson, a vice president of Browning Arms Co. (search), of Mountain Green, Utah, continued into the early afternoon. Superior Court Judge Edward M. Coleman did not indicate when he would rule.

Coleman halted the proceedings April 1 after the lead prosecutor admitted the evidence from Nelson should have been delivered to the defense last year. The admission came just after the defense rested and the prosecution prepared to call Nelson on rebuttal. The delay was to give defense lawyers and the judge time to review the material.

The defense is seeking dismissal of all charges and no retrial, because of "intentional and egregious prosecutorial misconduct that is part of a greater continuing pattern of deception."

Nelson took the notes and 25 photographs when he partially disassembled the shotgun on Feb. 5, 2003. The examination took place with no defense representative present, and the defense says evidence may have been altered or lost in the examination.

Prosecutor Steven C. Lember has said the delay in handing over evidence was an inadvertent mistake and said his office provided 6,000 pages of material to the defense. He accused the defense of using him as a "punching bag."

Legal experts have said they doubt Coleman will grant the request to throw out the case entirely, in part because they said it is unlikely Lember purposely held the material.

"I think a dismissal is just beyond the pale. You know how judges are loath to grant mistrials," said Robert D. Zatorski, a criminal defense lawyer and a former assistant prosecutor in Hudson County. "A fair trial doesn't mean a perfect trial."

Although the defense maintains the evidence dispute is "incurable," Zatorski said the judge could remedy the situation by allowing the defense to reopen its case.

The defense has maintained that Williams' shotgun, a 1993 Browning Citori 12-gauge, misfired when Williams snapped it shut while showing friends his mansion, killing Costas "Gus" Christofi (search), 55.

Williams, 36, is charged with recklessly handling the gun, and then trying to make the Feb. 14, 2002, shooting look like a suicide and persuading others to lie that Christofi shot himself.

Williams faces eight charges, the most serious of which is aggravated manslaughter. Collectively, they carry up to 55 years in prison. The least of the charges carries a penalty of up to 18 months in prison, but would likely result in probation.