An 18-year-old was stabbed through the heart near West Ruislip station in a row over stolen pasta.
Maxine Benson, 32, allegedly knifed 18-year-old Alfie Stone to death as pals egged her on after the teen was accused of taking food from a communal kitchen at a block of bedsits.
Alfie desperately tried to use a chip shop advertising board as a shield, but died from the wounds hours after the attack on November 9 last year, in High Road, Ickenham.
During Benson's trial, on Tuesday (April 5), the Old Bailey heard how Alfie's brother, Jake Stone, also sustained a serious wound to the chest, but emergency crews were able to save his life.
Benson's neighbours at the bedsits, Steven Hawgood, 28, and 29-year-old Corine Cripps, cried "Stab um, stab um" as she wielded the knife, before fleeing the area.
The pair checked into a hotel near Heathrow Airport, before being charged on November 12 , and Benson lay low with a friend until she handed herself into police the following day, and was arrested on suspicion of murder.
Brothers Alfie and Jake knew the Ickenham area well because Shannon was a tenant in one of the bedsits, although she had moved out a few weeks before the attack.
Benson, of no fixed address, and Cripps, of High Road, Ickenham, both deny murder and wounding with intent to cause grievous bodily harm.
Hawgood, of Kingston Avenue, West Drayton, also denies murder and wounding with intent.
Police confirmed Alfie Stone had been killed in the attack last November. He was said to have previously attended Pield Heath House School.
Defendant 'not happy' over Jake staying at bedsit
Two days before Alfie's death, Jake had stayed at the address following a fight with his mother.
Cripps tried to stop him from staying there, claiming Shannon Stone had been evicted.
Prosecutor Tony Badenoch QC said: “Corine Cripps had sought to prevent him from staying by saying, quite wrongly, that his sister had been evicted.
“Something which was untrue, not least as Shannon still had a key to the door and some of her belongings were still there.
“Quite why Corine Cripps was so concerned about somebody staying in a room which she did not herself occupy is unclear. Nor is it clear why she felt qualified to intervene.
“However, it does provide perhaps some assistance with why she might have felt quite so motivated towards the stone family a day or so later – because Jake had stayed at the address and ate food, something she was not happy about since it was in defiance of her.”
Two days later, on November 9, Jake and Alfie returned with some female friends to collect some of their sister's possessions, sparking the argument that cost Alfie his life.
When they got to the Ickenham bedsits, Benson and Cripps tried to stop them entering, with Cripps telling them 'This isn't a doss house'.
Cripps was heard shouting “Your sister has been evicted... get your sister here and I'll knock her out”.
The court heard she went to get her partner, Hawgood, who punched Alfie and was later heard shouting 'Stab em, stab em'.
Mr Badenoch said: “The argument continued with Maxine Benson, remaining at the top of the stairs and shouting at Jake about the pasta."
It was at this point Cripps allegedly passed something to Benson, possibly the seven-inch knife that killed Alfie.
Calling defendants 'crack heads' was the trigger for the attack
As the argument escalated, Benson was heard shouting "You mug, I'll smash your face in".
As they were leaving Jake shouted “You lot are crack heads”, with Alfie joining in, saying “Go and do some more crack”.
The prosecutor continued: “The suggestion that they either do, or should go and use some crack (cocaine) was a trigger to an escalation of this pointless argument.
“Corinne Cripps and Steven Hawgood shouted 'stab em, stab em'. It would seem that fists were no longer enough”.
The court heard Benson chased and stabbed both boys to the chest as they tried to flee down an alley way, killing Alfie and seriously injuring Jake.
Mr Badenoch said: “Her intention in chasing Alfie and stabbing him in the chest are clear, to kill him or at the very least to cause him really serious harm.
“The fact that the knife went into his chest and nowhere else on his body is clear evidence on her part of an intention to kill or at the very least to cause really serious harm.
“Both Corine Cripps and Steven Hawgood knew not only that Maxine Benson was capable of doing such a thing, but that she would do it right then and there with the knife that was now in her possession.
“Given the nature of the act they were encouraging, namely stabbing, it is the prosecution's case that they intended to further vent their anger and encouraged Maxine Benson with that knife to go on to inflict really serious harm, knowing that would happen."
He added that the fact that neither Cripps or Hawgood were with Benson in the alley when she stabbed the two boys was not a defence to murder.
The court heard that, after the killing, Benson passed the knife to a neighbour who cleaned it for her, and also lent her a clean pair of trousers.
When he asked her what had happened, she replied: "Don't worry, I think I may have hurt someone." The neighbour later handed the weapon over to police.
The taxi driver taking Cripps and Hawgood to a Travel Lodge near Heathrow said he heard Cripps on the phone saying: "They went to the house and they are even searching my bedroom."
When they were tracked down, Cripps told police they had booked into the hotel that with the police cordon and all the attention their block of flats was getting, they needed to get away from it all. But Hawgood claimed the two of them were off to a wedding.
Mr Badenoch said: 'Both of those lying accounts may lend support to the contention that they were keeping away from their own home for other reasons. They had been involved in the matters which are now before the court."
Benson is said to have confessed to a friend over the phone, saying: "My life's finished. I didn't mean to stab him.
"It happened in the scuffle in the alleyway. He was wearing a big puffa jacket. I didn't think it had gone in." She handed herself into Wandsworth Police Station the next day.