A second teenager is also on trial for the fatal stabbing
The trial has begun at the Old Bailey of two teenagers accused of the murder of Fulham man Omid Saidy, 20, in Parsons Green on 16 October.
Omid Saidy was stabbed to death in Parsons Green
Shafiq Smith, 18, of Brudenell Road, Tooting Bec and a 17-year-old who cannot be named, denied charges of murder and threatening a person with a bladed or pointed article in a public place in January.
Smith also denies the attempted murder of a third teenager, Oluwafem Omotosho, aged 19 and also known as Femi, of Pearscroft Road in Fulham. He has pleaded guilty to possession of a blade/sharp pointed article in a public place and affray, and has had his sentencing adjourned until the outcome of the current trial.
Prosecutor Timothy Cray told the jury that the police investigation suggested the victims as well as the defendants were carrying knives on the evening of Monday 16 October 2017.
He told the court that Mr Saidy was stabbed after chasing two suspected drug dealers from outside his home, near Parsons Green.
CCTV footage played to the court showed Mr Saidy initially walking after the defendants as Mr Omotosho rode along on his moped.
A fight involving Mr Saidy, Mr Omotosho and the defendants took place under the railway bridge on Parsons Green Lane, which is not covered by CCTV.
Mr Saidy was stabbed in the neck and pronounced dead at 8.30pm that night. Mr Omotosho was stabbed while lying on the ground after falling off his moped, but survived.
The prosecutor said to the jury: "Should they have chased the defendants? Absolutely not, dealing with drug dealers is the work of the police and the events show how quickly violence can spread if individuals try and take the law into their own hands.
"But did Omid need to die for the mistakes he made and did Femi need to be stabbed in the chest when he was lying on the ground?
"Those are the sort of very specific questions you'll need to focus on as you approach the evidence and reach your decisions."
Omid Saidy was a popular figure locally, having been a volunteer youth worker, with friends describing him as "one of the good guys" and tributes to him remained for months on fences and walls around the station.
April 19, 2018