Witness to 2009 murder 'told he would be charged' unless he gave Met a name

Fresh doubts have been cast over a 2009 gang murder conviction after the mother of the prosecution's star witness said he was threatened with being charged with the crime himself if he did not give police a name.

- Emily Dugan

Kai Shannon, 33, is 13 years into a life prison sentence for the fatal stabbing of 18-year-old Wahab Zaaki on the Attlee Terrace estate in Walthamstow, east London, on 13 March 2009. He has always insisted he is innocent.

Shannon was 17 at the time and he and Zaaki were junior members of a local gang known as the DM crew. No DNA linked Shannon to the crime, no motive was ever established and the clothes he was wearing that night had no blood or other forensic evidence found on them. The Criminal Cases Review Commission (CCRC) launched a review of the case in January. The decision came after the Guardian revealed analysis of a call between Shannon and another gang member, Rhys Williams.

In the recording of the call, made from prison, Williams can be heard telling Shannon he was "the sacrifice" and agreeing that he knew he did not kill Zaaki. Williams was key to securing Shannon's conviction and he was the only witness who told the court he saw Shannon stab Zaaki.

In a new development, Williams' mother, Petra Williams, said the police put pressure on her son. "They were going to charge him for murder if he didn't tell them who it was," she said.

After the attack, Williams was the prime suspect. His hand and wrist were injured that night but he left the scene before an ambulance arrived. He was arrested the next day and taken by police to hospital where he claimed he had been injured in a fight outside a club. Williams would not give an account to police but clothes stained with his blood were found in his flat when it was searched.

Poor-quality finger marks and DNA were recovered from the handle of a knife with Zaaki's blood on it found at the scene. While the evidence was too low quality to establish a positive identity, there was sufficient detail to exclude Williams.