The mother of murdered schoolboy Adam Regis has released a heartfelt appeal on the eve of the fifth anniversary of his death to find the men who killed him.
Regis, then 15, was killed in Plaistow, east London, on 17 March, 2007, while walking a friend home after a night out at the cinema.
The murderers have never been caught and witnesses have never come forward despite a £20,000 reward for information leading to a conviction.
Police were called at 9.30pm on that fateful night to reports of a stabbed teenager. Regis died an hour-and-a-half later at Newham General Hospital.
In the video an emotional Kristina Ceaser tells her son's assailants: "Please come forward. To you, to everyone, five years is a long time, but to a mother, it's hard."
She then turns to witnesses, saying: "The police have always said you don't have to give your name, nobody has to know it's you, you can phone up anonymously.
"I'm begging, please come forward."
She spoke fondly of her son's light-hearted nature, referring to him as a "joker" and a boy who was never on the streets.
Acting Detective Chief Inspector Andrew Kelly said: "It's been five years since Adam was murdered in a completely unprovoked attack. He was loving and caring to his friends and family and everyone speaks so highly of him. It's devastating for his family that his killers are still out there, living their lives.
"But five years is a long time and we can only hope allegiances [to the killer] have changed."
Regis' death had an impact on the local community with his school, Kingsford School in Beckton, dedicating a "garden of inspiration" to one of its star pupils.
Headteacher Joan Deslandes said: "The Kingsford memorial garden is a quiet, reflective place where students can go to be comforted and inspired.
"While the garden has been created in memory of those who our school community has tragically lost, it is also a place of inspiration and hope."
Detectives are looking for four suspects caught on CCTV and a fifth who was driving a car at the time of the incident.
They believe two suspects who got out of the car and ran toward Regis were Asian. Although the attack itself was not caught on CCTV, they see the pair dash for him minutes before he was stabbed.
Anyone with information is asked to contact the incident room on 020 8345 3775; if you wish to remain anonymous please call Crimestoppers on 0800 555 111.