A BBC investigation into the chilling murder in Reading, 65km west of London, has uncovered details about the days, weeks and months before the murder and the police investigation that followed.
In hundreds of messages and voice notes sent over Snapchat, the two boys revealed how they fell out with Olly online because he had seen an image of a younger boy being mocked and tried to make it stop.
When the two teen boys - who cannot be named because they are minors - found out about it, they accused him of "snitching" on them and set up a plan for revenge.
The messages show how they recruited a 13-year-old girl who was known to Olly to get him out of his home and into the open where they would ambush him, stab him to death and leave him in a pool of blood.
The BBC reports that in voice messages the teens sent to Olly, they told him: "You're going to die tomorrow Olly" and "I'll just give him bangs or stab him".
One voice note from the girl says that one of the boys "wants me to set him up" and "I'm so excited you don't understand".
Olly's father Stuart Stephens told the BBC the trio "hunted him, tracked him and executed him through social media".
According to the Sun, Olly's family was preparing to go back to work and school after the Christmas break when Olly received the message.
He told his family he would be back before dark. But a short time later, a knock at the door brought his family's world crashing down.
Olly had been stabbed repeatedly and despite the best efforts of friends and neighbours, he could not be saved.
The two boys were convicted of murder at Reading Crown Court last year and sentenced to 12 and 13 years respectively in a youth prison.
The younger boy's charges included murder and perverting the course of justice after he admitted getting rid of clothes he wore at the time of the attack.
The older boy was charged and convicted of murder, and two counts of perverting the course of justice for deleting apps on his mobile phone and throwing away clothes.
The girl pleaded guilty to manslaughter and perverting the course of justice by deleting data from her mobile phone.
She was ordered to spend just three years in a youth prison despite sending messages that read: "Karma - he deserves all of this".
Detective Chief Inspector Andy Howard, who investigated the crimes, told the BBC that there was an "unprecedented" amount of evidence in digital form - as much as 90 per cent of the evidence that helped convict the teens.
"We were taken aback by the amount of digital evidence," he said.
In court, Olly's father slammed the trio for what they had done.
Coming face-to-face with his son's killers in court, Olly's father relived the terrifying moment he sprinted to find his son dying.
On the witness stand, Stephens said the girl was "selfish" and that he blamed all three equally.
"The cruel actions of a vain, selfish girl has led to Olly being trapped and slain," he told the court.
"The day she walked into his life is a day we will forever regret. We as a family hold all three of you equally accountable for his death, there will be no forgiveness from us, ever.
"We are no longer the people we were and we will never be the same again."
In his victim impact statement, he went further.
"I had one job as a father, to protect my children, and I failed miserably," he said. "I will never forgive myself.
"Olly didn't deserve his fate no matter what he might have said or done, no child deserves such a callous fate.
"We will forever crave time with our son, the love of our child overshadows everything we do. It is because of jealousy and rumours that our son is gone.
"It turns my stomach daily to think of his final moments, to have him extinguished in this manner. One foul act has condemned us all to a miserable future."
