A 15-year-old girl recruited a gang of "teenage vigilantes" to lure a man to his death in the mistaken belief that he was a paedophile, a court in England has heard.
Lorry driver Darren Kelly, 42, from Basildon, Essex, was stabbed to death near his home in Pitsea, Essex, on October 20 last year.
Four people - including the girl, who is now 16 - are standing trial at Chelmsford Crown Court after pleading not guilty to murder.
Opening the trial, prosecutor Crispin Aylett described how the girl had launched a "personal campaign" against paedophiles.
She had previously arranged to meet two men she had found online in the hope they would be arrested.
By the time she spoke to Mr Kelly using the anonymous messaging app Whisper, she had "lost faith" in the police and court system, Mr Aylett said.
She arranged to meet him before telling her friends he was a paedophile and they plotted to ambush and attack him, he added.
Describing the case as being "as disturbing as it is extraordinary", Mr Aylett said there was no evidence Mr Kelly was interested in under-age girls.
He added: "In fact, there is plenty of evidence to suggest precisely the opposite."
Mr Aylett said: "The girl instigated this attack by forming a group of teenage vigilantes in order to attack a 42-year-old man that she had met online.
"She had told the others that the man was a paedophile and as a result he was punched, kicked and then stabbed to death in the street."
After the earlier incidents with two men, aged 23 and 67, whom she met on Facebook, officers asked her why she had arranged to meet them.
She told officers: "Because they're perverts and I don't think perverts should be around and I don't see anybody else doing anything about it."
Chris Carroll, 20, of Pevensey Close, Pitsea, along with two 17-year-old boys and the girl all deny murder. The teenagers cannot be named for legal reasons.
Mr Aylett said that although Mr Kelly had previously used the internet to meet women for sex, there was nothing to support the assertion that he was a paedophile.
In fact detectives found conversations with various women in which he said they were too young for him as he was looking for a partner who was over the age of 45.
Messages recovered by police suggested that Mr Kelly may in fact have believed he was meeting an adult, possibly the girl's mother.
On the day of the murder, the teenager arranged to meet him outside her school.
The other defendants, along with a 13-year-old girl, gathered nearby, with some of them hiding in bushes.
When he arrived, the group started to punch and kick him and Carroll slashed the tyres on his car, Mr Aylett said.
Mr Kelly managed to run away but the group chased after him.
Witnesses described seeing him running for his life.
Mr Aylett said: "In the moments leading up to the murder, as they were chasing him through an alleyway, a passer-by asked the group what was going on.
"Perhaps indicating the inflamed sense of self-righteousness shared by the others, Chris Carroll shouted out 'He's a paedo'."
Another witness described how they punched and kicked him to the ground before Carroll was heard saying "Leave it to me". He was seen bending down as if to stab him.
Mr Kelly managed to get help from residents at a nearby block of flats.
But he had been stabbed six times, including two wounds to his lung, and died later in hospital.
After the attack, the group went to a house and ordered pizza.
The two teenage boys were later handed in to police by their parents.
When officers arrived at a house to find Carroll and the girl, he tried to escape while she shouted: "Do I look like a murderer?"
Mr Aylett said text messages later showed that Carroll was besotted with the girl.
One said: "I know you're not ready for a relationship but I'm going to wait for you.
"I'm not going to quit until you're mine."
The 13-year-old was arrested but later released without charge, the court heard.
The case is expected to last about four weeks.