SAN JOSE -- As police probed for answers to why he would fatally stab a high school classmate he'd befriended, 15-year-old Jae Williams struggled to explain. The boys weren't close friends. His religion -- Satanism -- allows killing. And he'd already slain a rabbit and beaten a cat to death.

"I guess I just finally wanted to kill somebody," Williams told detectives two days after the November 2009 slaying of Michael Russell, 15, according to a transcript of the interview. "I had my chance and I took it."

While prosecutors have long claimed that Williams confessed to killing Russell with the help of alleged accomplice Randy Thompson just for thrills, documents recently made public as the case heads for trial reveal chilling new details about the teen's slaying.

The accused young men, now 20, implicated each other in separate statements they gave to police. But Williams also made a full confession, prosecutors allege, revealing the victim's last words and their cold-blooded motive.

Although the young men's statements are not the only evidence against Williams and Thompson, they will play a significant role in the upcoming case, which is finally coming to court four years and five months after Russell's slaying.

But in a twist, there won't just be one trial -- there will be two. Williams, who was 15 at the time of the killing, will be tried first, with a trial that is expected to start by the end of the month and stretch an estimated six weeks. Thompson, who was 16, will go next, under a recent court ruling. Both will be tried as adults and face life sentences if they are convicted.

Williams' defense attorney, Lewis O. Romero, fought for weeks recently to exclude Williams' damning statement from his trial, arguing the young man's rights were violated, partly because he was kept overnight at the police station for 12 hours before being read his rights. But the judge ruled the interview could come in, noting among other things that the teen came to the station voluntarily with his mother's permission, was treated well by police and allowed to slept intermittently for nine of the 12 hours.

The judge won't rule until after Williams' trial whether the prosecution can use Thompson's statement in his trial over his attorney's objections. His statement isn't available to the public but puts the blame on Williams, according to court sources.

Russell's relatives, who are already frustrated by the delays, were "shocked" to learn there would be two separate trials, said Donna Russell, one of his four aunts.

"We don't want to sit through it twice," said Cathy Russell, another aunt. "But if this is what it will take to get it done, we want to move forward. We will not miss a day of either trial."

Judge Arthur Bocanegra split the case because of the incriminating statements each defendant made about the other in their police interviews, and prosecutor Valerie McGuire wants to use those statements to help convict them.

Dual-jury option

That left the judge with two difficult choices. He could have allowed two juries to hear the case at the same time, as McGuire sought. In that event, each jury would hear only the statement of the defendant it was evaluating and would leave the courtroom when the other defendant's statement was introduced.

Dual juries are common in Los Angeles County and occasionally used elsewhere, including Sacramento County. But only one dual jury has been convened in Santa Clara County in the past 14 years, in a 2010 carjacking case in which both defendants were convicted. The advantages of two juries hearing a case one time is it saves time and money and spares witnesses from having to testify twice.

However, Bocanegra chose to hold two separate, consecutive trials, partly because of the difficulty of fitting two juries into a single courtroom. Williams' jury will learn he was brought to the police station about 8 p.m. and revealed details of the encounter the next morning.

Williams said he and Thompson began looking for opportunities to corner and kill Russell about six weeks before they allegedly attacked him in his backyard.

"Day by day, we would ... ask if he was doing anything or if he was going anywhere, if he wanted to chill with us," Williams told detectives.

The attack

He told police he and Thompson strolled over to Russell's house about 6 p.m. Nov. 10 with their weapons, prepared to attack.

The admission that they had deliberately set out to kill Russell is important because to try both young men as adults, the prosecution needed to charge them with first-degree murder, which requires either that the crime was committed during the commission of another felony or was premeditated.

Williams said they even had crafted two alibis -- that they were in Thompson's backyard the whole time or with friends -- according to court records. Russell answered the door in his pajamas that evening, and the teens invited him to smoke "weed," Williams claimed. No one else was home.

Russell pulled on some clothes and met them in his backyard. Realizing they needed a lighter, Russell tried to get one from the house but found he had inadvertently locked himself out. He began searching for one in a shed, Williams said. When he came out of the shed toward the picnic table, the attack began.

Tackled onto the grass, Russell tried to reason with the boys he thought were his friends while wriggling onto a paved portion of the yard, Williams said.

"He was on the floor, and he was yelling a little bit," Williams said, "like telling us ... 'Come on, guys.' "

But it was no joke. The attack continued for a "good six minutes," Williams said, adding that he capped it by slitting the slender boy's throat -- after feeling for Russell's pulse and finding none.

Russell's uncle found his bloody lifeless body in the yard that night. Police said he'd been fatally stabbed with a switchblade and kitchen knife.

Two days later, detectives asked Williams at least six times why he killed Russell.

"It might not be a very good reason, but there is a reason," Williams said. "'Cause we wanted to."

Contact Tracey Kaplan at 408-278-3482.