A teenager has gone on trial accused of murdering a man who was trying to stop a mugging.
Liam Attwell died three days after being stabbed
Bristol Crown Court heard that Liam Attwell was attacked by a teenage boy as he tried to intervene in a mobile phone robbery in the Canon's Marsh area of Bristol.
Mr Attwell was stabbed once in the chest when he confronted a group of youngsters who were robbing three teenage boys on the afternoon of 3 October last year.
The 25-year-old chef died in hospital three days later.
A 17-year-old from Bristol, who cannot be named for legal reasons, denies murdering Mr Attwell.
Richard Smith QC, prosecuting, said the defendant was part of a small group on bikes who bullied, intimidated and robbed three teenage boys from Chippenham, Wiltshire.
The defendant threatened one of the boys with a knife, the court was told.
Mr Smith said: "Liam Attwell came upon that scene by chance and to Mr Attwell's credit he went to the assistance of the three teenagers who were being robbed."
The robbery victims managed to escape and saw Liam Attwell arguing with the boys.
The court heard how some "pushing and shoving" ensued and when Mr Attwell took hold of the defendant's bike, the defendant's friends gathered around him.
The prosecutor said one of them took a bike seat and hit out at Liam Attwell and the defendant took out a knife and stabbed him once in the chest.
The defendant and his gang then cycled off.
Mr Attwell collapsed and did not regain consciousness.
The defendant was arrested five days after the stabbing.
The trial is due to last four to five days.