This CCTV footage shows the moment a man with a mental age of nine was fatally stabbed in the heart after refusing to hand over his belongings to robbers.
Dean Mayley, 24, was held up by four men described by police as "cowards." They were all convicted of involvement in his death after driving around Greenford in West London on February 7 looking for someone to rob.
They spotted Mayley and three of them got out - one to threaten him and the other two to block his route and avoid any chance of escaping.
Mayley had a mental age of nine due to a brain disorder and police believe he did not understand what was happening.
CCTV captured the moment Dean Mayley was stabbed
After the attack, he staggered into the street and collapsed.
Passers-by went to help him and an ambulance took him to St Mary's Hospital where he died two hours later.
The four men were convicted at the Old Bailey of his death on Thursday.
Jamal Jones, 17, who wielded the knife, was found guilty of murder and attempted robbery.
Michael Mensah, 18, was found guilty of manslaughter and attempted robbery. He was also found guilty of robbing a 15-year-old boy in a separate incident.
Miguel Leiba, 17, was found guilty of manslaughter and attempted robbery;
Ryan Beresford, 19, was found guilty of manslaughter and attempted robbery.
All four were convicted at the Old Bailey. They will be sentenced on October 2.
Dean Mayley (left) with his nephew Callum
Detective Inspector Mark Lawson from the Homicide and Major Crime Command, said: "The defendants were a team of robbers who, armed with a knife, were scouring the area that day looking for someone to rob.
"They had not a moment's hesitation in using that knife when Dean didn't immediately hand over his property. The knife was plunged into his heart; there could be no doubt of the defendants' intentions.
"Dean's family remain horrified and devastated by his needless death at the hands of these cowards and I hope their conviction today goes some way to helping them begin to move forward with their lives."
Donna Mayley, - Dean’s mother, said her son's death had "ripped our family apart".
“It is so hard to comprehend that we will never see him again," she said in a statement after the verdicts.
“My Dean had only just started travelling alone. He used to travel around with his dad up until his dad passed away in June 2013. Dean would make the simple trip from our home to his uncle’s house in Greenford. He was murdered for nothing at all.
"Our family will never be the same again, the youngest of our family has had his life cut short for no reason and we will all struggle to come to terms with this for the rest of our lives.”