Campbell called for a fresh investigation of the murder of the Doyle family, accusing Tam McGraw both of the original murders and of instigating a campaign over 20 years to ensure that Campbell remained in jail and was silenced, including repeated attempts on Campbell's life. But commentators considered it unlikely that a fresh investigation would be launched as a result of the convictions being quashed and the fresh evidence that had been presented since the original trial. This was in part because claims by Campbell against a man whom he is regarded as hating are viewed with scepticism (his stabbing in 2002 was believed at the time to be part of a long running tit-for-tat feud between the two men), and in part because two police officers who had been heavily involved in the case had since died: Detective Superintendent Norrie Walker in 1988 and Detective Chief Superintendent Charles Craig, head of the Criminal Investigation Department at the time of the murders, in 1991.