Tarek Chaiboub, aged 17, was shot with a sawn-off shotgun outside a barber's shop in Burngreave because he was seen as a "traitor" by some of the gang.

At the start of the trial of four people accused of murder Paul Watson QC, prosecuting, told Sheffield Crown Court: "Last year a young boy was shot dead outside a shop on a street corner. It happened in broad daylight. It was a pre-planned and cold blooded execution.

"Those who did it knew exactly what they were doing. In fact an earlier attempt to kill the same boy had failed. This time they made no mistake.

"This was not Chicago in the 1930s. Still less was it the East End of London in the 1960s. This happened less than a year ago on a Friday lunchtime on a busy thoroughfare."

Jurors heard that the gang, which operated in Burngreave and Pitsmoor, had suffered a serious split and Tarek, who lived in Castledine Gardens, Wincobank, had a "foot in both camps".

The warring had already resulted in the murder of one member on one side – Brett Blake – and the attempted murder of another member on the other side – Junior Liversidge, who was a cousin of two of the defendants.

Two days before he was shot last July, Tarek was almost killed in a stabbing attack outside his home.

Mr Watson QC said the teenager was blamed for passing on information to gang members Esmond Thompson and Isiah Nelson, which led to them stabbing 19-year-old gang member Junior Liversidge "to within an inch of his life".

Tarek was friends with both the attackers as well as the victim and his death is said to have been in "revenge" for helping to locate Mr Liversidge on the night he was knifed.