Early on the afternoon of Jan. 3, 2001, authorities in the tiny Rocky Mountain outpost of Guffey, Colo., found Carl and JoAnna Dutcher dead from multiple gunshot wounds inside their home.
Immediately, investigators sensed that this was no ordinary crime, yet it would take months for them to unravel the bizarre circumstances that culminated in an unspeakable triple homicide: Was it all a twisted version of the children's game Simon Says?
After discovering the Dutchers' bodies, investigators quickly zeroed in on their 15-year-old grandson, Tony. He had been visiting at the time of the murders, but was nowhere to be found.
Police called the boy's mother, Jennifer VanDresar.
"I just kept saying, 'You have to find my son, he's hurt, you have to find him,'" she remembered telling the police. "Then it came to me ... and I said, 'He's in the fort.'"
The "fort" was a makeshift campground about 100 yards up a hill overlooking the Dutchers' home.
Here, in this place meant for innocent play, investigators would discover another horrific crime scene: Tony's body was found in a sleeping bag, his throat slashed almost to the spine.
Alongside the body lay an unfinished Scrabble game, a clear indication that Tony had not been camping out alone that night.
Tony's mother told police that Isaac Grimes, Tony's one-time best friend, was supposed to be joining her son for a camp-out.
Initially, Grimes denied being anywhere near Tony Dutcher on the night of the murder, saying he hadn't seen him since school let out for Christmas. Eventually, under pressure from his mother to tell the whole truth, Grimes made a shocking confession: He had killed Tony.
Not only did he confess to the murder, but he also told investigators the entire twisted story leading up to Tony's brutal death: The murder was a test of his loyalty to Simon Sue, leader of a bizarre paramilitary cult called the Operations and Reconnaissance Agents, or O.A.R.A., and made up of seemingly harmless high school boys.
In an exclusive interview with "Primetime," Grimes shared the details of his horrible crime -- revealed to police back in 2001 -- for the first time in public.
Grimes' Chilling Confession: 'We Played Some Scrabble, and Then I Murdered Him'
On New Year's Eve 2000, Grimes's friend -- and fellow O.A.R.A. member Jon Matheny -- dropped off the boys at the Dutchers' remote mountain home. After dinner, Grimes and Tony climbed to the fort.
That's when a night of innocent fun would turn deadly.
"Up at the top of the hill we talked for a while, we played some Scrabble, and then I murdered him," Grimes told ABC News. "He was wrapped in his sleeping bag. I pointed out what I said was a light in the distance that I wanted him to look at and I kept saying, 'Well, no, you're not seeing it.' So I got behind him and I murdered from there."
But what about Tony's grandparents, Carl and JoAnna Dutcher?
Grimes insists that he is not responsible for their deaths. Instead, he says that Matheny returned to the Dutchers' home and shot them. Then the two boys gathered weapons from the house, loaded them in the car and left.
On the drive back from the mountains, Grimes also says Matheny made a phone call to alleged O.A.R.A. ringleader, Simon Sue -- in Canada with his family at the time -- to tell him that the grizzly mission had been accomplished.
"[Matheny said] something like 'He did it' or something like that, referring to me," Grimes said.
Only after a lengthy interrogation did Sue finally tell investigators about the phone call, in which Matheny had implicated himself and Grimes in the killings.
Sue described the substance of the phone call in stark terms: "Isaac killed Tony and Jon killed the other two."
Click here to watch Sue's shocking admission to police.
Ultimately, all three boys would plead guilty before their cases could go to trial. Grimes admitted to Tony's murder, while both Matheny and Sue pleaded guilty to conspiracy to commit murder, as well as violating Colorado's organized crime laws.
All three received harsh sentences: Grimes is currently serving 60 years in prison; Matheny, 66 years; and Sue, 53 years.
Yet despite these guilty pleas, the full story behind the murders -- now almost nine years old -- remains elusive. And of course, the questions remain: Why did they do it? Had this high school senior brainwashed two younger boys into committing an unspeakable crime?
Alleged Cult Leader Dismisses Brainwashing as 'an Easy Defense'
Matheny's account of New Year's Eve 2000 differs from both Sue's and Grimes's. Although he has confessed to being the driver on that fateful night, Matheny said that not only did he not murder the Dutchers, but that he was never even inside their house.
He also claimed the whole thing was a burglary gone wrong, but he provided little in the way of details.
"There was no motive other than we wanted the guns. It went from being a burglary to a triple homicide like it is, with no point to it," Matheny told ABC News.
Matheny said he does not know who actually pulled the trigger.
"I can't say, I wasn't there," he said.
Meanwhile, Sue scoffed at the portrayal of him as some kind of evil genius. In fact, he said he is not even that smart.
"You know, if you look at my high school records, I did poor in school, you know," he said. "My IQ, I'm not a genius by any sorts, in fact I have an average IQ."
Sue also rejected the characterization of him as a charismatic cult leader in training, a budding Jim Jones.
"Charisma is in the eye of the beholder," he told "Primetime."
Sue said his O.A.R.A. was little more than a boy's club; everything else is a figment of Grimes' imagination, especially claims of brainwashing and indoctrination.
"Isaac Grimes says a lot of things and it's an easy defense," Sue said.
However reluctantly, Sue did admit to ABC News that the O.A.R.A. was a highly organized group, that he was its undisputed leader and that they committed other crimes like stealing guns.
What about Grimes's belief that the O.A.R.A. was a worldwide operation whose secret mission was to fend off armed insurrections in the tiny South American country of Guyana? Even authorities initially found the stories about the group convincing enough that they provided Grimes and Matheny with armed guards and bulletproof vests.
Sue refused to take the credit for these grandiose ideas.
"Anything that Mr. Grimes has said about O.A.R.A., I never led him to believe any of those things," he said.
Nine Years After Triple Homicide, Tragedy and Recriminations Persist
Sue said he only pleaded guilty because his mother begged him to, fearing that in the aftermath of the terror attacks of Sept. 11, 2001, someone with a "foreign appearance" like his would get a life sentence.
Sue's mother, Nadia, has written to Grimes in an effort to vindicate her son. Grimes has responded to her in letters and has also written to the district attorney, sometimes claiming he acted alone.
"This is what Isaac writes, 'During my testimony, under oath ... I knowingly and willingly lied,'" Nadia read from one of Grimes's letters.
But these letters are also filled with outrageous rants, and Grimes's parents said they only show the full effect of his illness and the corrosive guilt he feels over killing his best friend.
Perhaps the most tragic ending of all is what has happened to Tony's mother, Jennifer Van Dresar. Her despair led to drinking and taking pills and two suicide attempts. Then one awful night, VanDresar, under the influence, drove the wrong way down the interstate and killed a 27-year-old father. She was sentenced to five years in prison.
VanDresar now writes letters to Grimes, her son's killer. Despite her pain, she has compassion for him, a boy who at 15 was convinced that he had to kill in order to protect his family and save himself.
"I think in Isaac's little teenage mind, he did what he thought he had to do, he didn't know there were other choices," VanDresar said.
Grimes, now 23, said that for him, one thing is certain.
"I am a murderer for life now," he said. "I can't take that back. I did a horrible thing, and I can't take that back."