Four guilty of killing Dean Mayley in Greenford mugging
Four teenagers have been convicted at the Old Bailey of killing a man with a mental age of nine who was stabbed during a mugging in west London.
Dean Mayley, 24, was stabbed in the heart while walking alone in Ruislip Road in Greenford in February.
Jamal Jones, 17, from Acton, who wielded the knife, has been convicted of murder.
Michael Mensah, 18, Ryan Beresford, 19, and Miguel Leiba, also 17, were convicted of manslaughter.
Mensah, of Greenford, and Beresford, of Acton, along with Leiba, from Hanwell, were also found guilty of the attempted robbery of Mr Mayley.
Jones, who was found guilty of murder, had earlier pleaded guilty to a charge of attempted robbery.
All four will be sentenced on 2 October.Hunted victims
Lifting an order banning the naming of the 17-year-olds, judge Martyn Zeidman QC said: "Yet another example of a kind and innocent person losing their life because of somebody else using a knife.
"I just wish there was some way - obviously there isn't - in which I could turn the clock back."
After the verdicts the victim's mother Donna Mayley said: "It's never going to bring Dean back.
"Dean was a lovely lovely boy. Everyone that knew him loved him.
"I can't believe it happened - and for nothing. He was my youngest son and it's affected the whole family. It's unbearable."
During the trial prosecutor Simon Denison QC said: "These four were a team of knife-point robbers driving up and down the Ruislip Road looking for a victim or victims."
A CCTV camera captured the fatal attack in which three shadowy hooded figures are seen approaching and confronting the victim before one of them lashes out with a knife.
Mr Mayley, who had learning difficulties due to a brain condition called Microcephaly, collapsed in the road and later died in hospital.
Following the verdict, Baljit Ubhey, London's Chief Crown Prosecutor, said: "This was a cruel and callous attack on a vulnerable victim.
"Dean was a vulnerable young man and it is likely that he did not understand what was happening to him in this terrifying situation."Meat cleaver
Mensah was also found guilty of an earlier robbery which took place in the same area on 28 January.
At that instance he was involved in the mugging of a 15-year-old boy who was forced to hand over his North Face bodywarmer and mobile phone in the same area, the court heard.
While they were awaiting trial Mensah wrote a letter to Jones to persuade him not to implicate him in the murder, and further asked him not to say it was Mensah who had given him the murder weapon or told him to carry out the attempted robbery.
A search of Jones's bedroom uncovered a kitchen knife stashed under his mattress and a meat cleaver on top of his wardrobe.Letter from Michael Mensah to Jamal Jones
In the letter Michael Mensah wrote to Jamal Jones in May while he was being held at HMP Feltham, Mensah ordered him not to say he had given Jones the murder weapon and advised Jones on his defence.
Mensah wrote: "Why do they think I gave you the nank (knife) and persuaded you? They can't say that without proof.
"I don't know why I came (to Greenford), I should have never come, it's only coz I was bored.
"Never in your life, say out loud I told you to rob anyone..."
Regarding Jones's defence, Mensah wrote: "Why are you saying self defence?
"If you want manslaughter you have to say you was off a drug. Say you take Molly (ecstasy)..."
Mensah went on to write that he cannot be convicted under joint enterprise as there was "never a enterprise to join" and he was not involved in the robbery, "so I'm not liable".
"You did the robbery but you wasn't in control, your mental state wasn't correct so doing it wasn't your fault so it's manslaughter."
Writing in capital letters, Mensah asked Jones to stop acting like a kid and "come correct big man ting".
Mensah also had previous convictions over the possession of knives, the court heard, with police discovering a five-inch jagged blade in his trainer and a samurai sword in the boot of his Fiat Punto in September last year.
This January he was stopped in his car again and a lock knife was found underneath the driver's seat.