A fragment of circuit board alleged to have been part of the bomb's timing mechanism is the sole item of physical evidence linking the two Libyans to the December 1988 bombing. But Tam Dalyell, Labour MP for Linlithgow, declared: "I have come to suspect that the timing device in question was not that of Pan Am 103 but a different timing device that the CIA had picked up from the Libyans ... I have been driven to the conclusion that the device was a CIA plant."
Mr Dalyell, a long-standing critic of US and British government insistence that Libya was behind the attack, said an analysis of the fragment had shown it had been exposed to a temperature of 4,000deg C. But a Swiss police specialist had cast doubt on this, saying the explosion would have lasted only a fraction of a second in outside air temperatures of about minus 40C.
Accusing the Crown Office, the Scottish prosecuting authority, of failing to follow up the right leads, Mr Dalyell said - to strident denials from Lord James Douglas-Hamilton, the Scottish Office minister - that it had allowed itself for six years "to be suborned by political pressure into failing to carry out its duty".
He said this was a "wicked" dereliction of duty that brought shame on Britain.