He was wrongly convicted of manslaughter in 1981, for which he spent six years in prison, until 1987. The conviction was later quashed in the light of new forensic and other evidence that raised serious questions about the dubious nature of the evidence used to convict Wallace initially. Incredibly, the Court of Appeal heard that scientific evidence used to convict Wallace was false and that the Home Office pathologist involved in the case admitted that he had received it from an anonymous American security source. The journalist Paul Foot, in his book "Who Framed Colin Wallace?", suggested that Wallace may have been framed for the killing, possibly to discredit the allegations he was making. This view was similarly expressed by Alex Carlile QC (now Lord Carlile), who later speculated that this may have been the motive not just for the alleged frameup, but also for murder.