A Fairfax County judge yesterday denied a new trial to a Springfield man serving a 30-year prison sentence for the 1997 killing of a teenager, even after the judge saw a videotape of another man confessing to the attack.

Circuit Court Judge R. Terrence Ney said it would be difficult to determine whether the confession is reliable. But Ney said he cannot even consider the possibility because Virginia law forbids defendants to introduce new nonscientific evidence more than 21 days after sentencing.

"Even if it were deemed to be a genuine confession, it was furnished a long time after the conclusion of trial," Ney said.

Ney's decision came in the case of Mario A. Bustillo, 23, who was convicted of first-degree murder in the Dec. 10, 1997, slaying of James R. Merry, 18, of Springfield. Prosecutors said Merry was standing outside a Popeyes restaurant in Springfield when Bustillo mistook him for a member of a rival gang and smashed him in the head with a baseball bat.

Three eyewitnesses named Bustillo as the attacker during a 1998 trial. But Bustillo said he has compelling evidence -- including a videotaped confession from a man named Julio Cesar Osorto -- that shows he didn't do it.

Because Virginia's strict evidence rules do not allow Bustillo's defense team to present the videotape as new evidence of innocence, his attorneys tried to win a new trial by showing that prosecutors violated procedural rules.

The state Supreme Court is considering loosening the 21-day rule to allow certain defendants to present new evidence "within a reasonable time after the discovery of the evidence." The Judicial Council, made up of judges, legislators and lawyers, is scheduled to meet Monday to make a recommendation to the court.

In Bustillo's case, his attorney, John C. Kiyonaga, argued that authorities failed to turn over evidence that could have been helpful to the defense. Prosecutors only recently gave him a photo of Osorto and a police report showing that Osorto was stopped by officers near the scene of the attack and had red stains on his shirt.

Ney rejected the procedural challenge. He noted that Bustillo's trial attorney presented evidence that Osorto was the killer and that the jury discounted that testimony. "The jury considered that evidence, and the jury rejected it, finding that Mr. Bustillo was indeed the assailant," Ney said.

But Kiyonaga argued that at the time of trial, the defense attorney did not know Osorto's full name -- referring to him only by his nickname, "Sirena." Prosecutors dismissed him as the "so-called Sirena," implying he was a phantom, Kiyonaga said.

Jurors might have reached a different conclusion if they had known that, "yes, that individual does exist. He was on the scene. He fled the scene. And he had stains on him," Kiyonaga said.

But Ney agreed with state Assistant Attorney General H. Elizabeth Shaffer, who said the admission of the police report would not have made a difference at Bustillo's trial. He also found that police did not obtain the photo of Osorto until long after sentencing and were under no obligation to give it to the defense.

Shaffer said in court that Kiyonaga was inappropriately using the procedural argument to "revisit claims of innocence."

Christopher Amolsch, an Alexandria lawyer who is not involved in Bustillo's case, said arguing procedural flaws is the only strategy available to defense lawyers trying to exonerate convicts.

"Virginia law is almost designed to prevent actually innocent people from showing that they are innocent," Amolsch said. "Even if the judge believes he has the wrong man in jail, he's powerless to do anything about it."

Amolsch faces a similar situation in the case of Aleck J. Carpitcher, a Roanoke man serving a 38-year sentence after being convicted of molesting his girlfriend's daughter. The girl has since said that she lied, but the judge can't consider the fact that she changed her story.

Yesterday, Ney allowed the tape, which was secretly recorded in Honduras in 1998, to be played in court for the first time even though he was not considering its authenticity. The video, recorded by a Bustillo family acquaintance, shows the acquaintance talking in Spanish with Julio Cesar Osorto about the attack.

Osorto recalled that he became angry and struck Merry after he spotted him "throwing [gang] signs," according to a translation.

"I shoved it down with one whack. . . . Man, that was loud," Osorto said on the tape.

The Virginia Court of Appeals and Virginia Supreme Court have upheld Bustillo's conviction, and the U.S. Supreme Court declined to consider the case.

Kiyonaga, who has represented Bustillo for five years and has traveled to Central America three times to investigate the case, said he remains convinced that Bustillo will be exonerated. He said he plans to appeal the judge's ruling.

"This is so wrong," Kiyonaga said.