Victoria station stabbing CCTV footage released
24 April 2013 Last updated at 18:34 BST
Police have released shocking footage of a gang of 20 youths as they pursued a 15-year-old boy before stabbing him to death.
Sofyen Belamouadden was murdered in full view of commuters in the ticket hall at Victoria tube station three years ago.
The clash between two gangs was organised on Facebook and is the largest so-called joint enterprise case ever heard in the UK.
Sangita Myska reports.