SAN JOSE -- Wailing in anguish, the uncle of a 15-year-old Santa Teresa High School student begged his nephew to "come back, please come back to me" as he tried in vain to resuscitate the boy's knife-ravaged body, according to a brief 911 tape played for the first time Tuesday in court.

The short tape, played by the prosecution on the opening day of a murder trial for Jae Williams, one of slain classmate Michael Russell's accused killers, drew tears from many in the packed courtroom, including one of the men on the jury who took off his metal glasses and dabbed at his eyes.

Williams and Randy Thompson, now both 20, are accused of stabbing Michael to death in November 2009 for the sheer thrill of it after befriending him. They are being tried separately as adults, with Williams going first in a trial expected to last four to six weeks.

The attack took place in Michael's backyard on Comanche Street in South San Jose early in the evening. Williams and Thompson lured him out to smoke marijuana and then tackled him, pinning him down so they could each stab him, prosecutor Valerie McGuire contended in her opening statement.

Williams listened impassively to the six-minute 911 tape that captured Michael's uncle, Thomas Russell, trying desperately to administer first aid. Because the uncle had his cellphone on speaker during the emergency call, even the thumping sound of him compressing Michael's chest was eerily discernible.

"He's been stabbed, oh my God, please, somebody help me," Thomas Russell sobbed as the 911 operator sought to calm him down and get an accurate address. "Come on, son ... no ... no ... Michael, come back."

Michael suffered at least 12 significant stab wounds, one of which perforated his larynx, jugular vein and carotid artery and another that collapsed his right lung. Another penetrated 7 inches deep through his chest and into his heart. His hands were nicked when he tried to defend himself.

"Jae Williams and another boy -- cloaked in friendship -- went to Michael Russell's house and unleashed a ferocious attack," McGuire said in her 75-minute opening statement. "The truth is, they butchered him."

Williams' attorney, Lewis O. Romero, reserved his right to present an opening statement in his defense until after McGuire finishes her case. Both young men face life sentences if they are convicted.

McGuire must prove Williams is guilty beyond a reasonable doubt. But she said she can do better than that, based on the evidence, including DNA and an alleged confession Williams gave to police after they got a tip about his involvement.

"He is guilty beyond any reasonable doubt," she said.

Despite the severity of his wounds, Michael didn't bleed much, probably because many of them were so devastating that they slowed down the rate at which his heart was pumping blood, Santa Clara County pathologist Dr. Joseph O'Hara testified Tuesday afternoon.

Williams, who was 15 at the time, talked to police a few days after the Nov. 10, 2009, attack, which occurred after Michael's mother left to go to Target, seemingly bragging that he and Thompson long planned to kill Michael.

They took a chef's knife from Thompson's mother's kitchen, Williams said, which McGuire showed the jury on a screen. The knife looked ordinary, except it was streaked with Michael's blood, DNA tests concluded, she said.

After killing Michael, Williams and Thompson wrapped the weapon and a serrated knife that may not have been used in the attack in some clothing and casually discarded the bundle in Thompson's driveway, between two cars, the prosecutor said. Thompson's father found it and one of Thompson's sister's friends reported it to police.

Police also retrieved sweatshirts belonging to Williams and Thompson that they'd discarded in the bushes nearby, based on information provided by Williams. Both items of clothing had Michael's blood on them, McGuire said.

Williams reportedly told police he killed Michael for several reasons, including that they were not close. He also said he worshipped Satan and had already beaten a cat to death.

Thompson was particularly keen to make his first human kill, Williams told police. Tuesday, McGuire said the two boys were so close they exchanged rings and gave each other nicknames -- Grimm and Goure, which she said stood for grim and gore.

"Two rings, two friends, two sweatshirts, two knives," McGuire said, "and one boy who had no chance, absolutely none."

Contact Tracey Kaplan at 408-278-3482. Follow her at Twitter.com/tkaplanreport