Detectives have made a fresh appeal for witnesses to the murder of teenager Jessie James, one year after his death.Jessie, 15, was gunned down in Moss Side in Manchester on September 9 last year.Like the death of 11-year-old Liverpudlian Rhys Jones, Jessie's killing sparked national soul-searching over the rise of gang culture and gun violence on Britain's streets.Both his family and police have appealed to the community to break down the "wall of silence" surrounding the youngster's murder.Jessie was shot dead as he rode his bicycle through Broadfield Park in the early hours of the morning.At the inquest, coroner Nigel Meadows took the unusual step of allowing witnesses to give evidence anonymously via video link to Manchester Crown Court, with their voices disguised and their identities concealed.The hearing was halted dramatically after a new witness came forward during the inquest and as a result a 21-year-old man from Old Trafford and a 20-year-old man from Hulme, both prison inmates, were arrested pending further inquiries.Detective Superintendent Shaun Donnellan, senior investigating officer for the murder, said: "It may be a year since Jessie was killed but I am sure there are still people out there who have information they have not yet given to the police."We have protective measures in place so no-one ever needs to know who you are but your testimony could be the piece of the jigsaw that convicts his killers."Police said they thought Jessie's murder was a case of mistaken identity and that he was "in the wrong place at the wrong time".But his mother Barbara Reid told the inquest he was killed for refusing to join a gang.CCTV footage showing people cycling away from the murder scene was released and the offer of a £20,000 reward for information is still being offered.Despite the numerous appeals from Jessie's family and police, no-one has yet been charged with his murder.His mother and sister, Rosemary, are understood not to have planned any public events to mark the murder anniversary.© Independent Television News Limited 2007. All rights reserved.