London police seek new witnesses in 1993 Stephen Lawrence killing LONDON, April 30 (UPI) -- A possible new witness to the racially charged 1993 Stephen Lawrence killing responded to a television appeal Monday, London police said. The case was featured on BBC's Crimewatch, the Daily Mirror reported. Detective Chief Inspector Clive Driscoll, the lead investigator, said at least one call after the program looks promising. "It actually does move us forward with a potential suspect, which is very encouraging," he said. We also have a possible motive which all adds to what we know. So far it's been very encouraging. Lawrence, an 18-year-old student who hoped to be an architect, was stabbed as he and a friend waited for a bus in South London on April 22, 1993. The friend said Lawrence's attackers used racial slurs. The Macpherson Report in 1999 suggested the investigation was mishandled by police partly because Lawrence was black. Two men were convicted in 2012, and police have said they will bring others to justice. On Crimewatch, investigators said they were looking for a man wearing "a distinctive green jacket" with a large V on it and for two men who got off a bus on the other side of the street. Doreen Lawrence, Stephen's mother, was interviewed for the program. "He did not die by accident," she said. Why should he be denied his life because of the color of his skin? Stephen's life has meant so much and he deserves to make sure all his killers have been caught.