London - (Preposterous Nonsense Update): Cops are working on a theory that the dead MI6 codebreaker 'had a secret identical twin brother' who freelanced doing impersonations for a living.
"That way Williams could have gone on any number of secret undercover assignments without attracting unwarranted attention," the head of forensic genealogy commented today.
"Another possibility is that this 'alleged twin brother' - let's call him 'Dai' - suffered a narcoleptic fit during a visit to his brother's apartment.
"That would explain an awful lot of things - not least of which is some dodgy CCTV footage trawled out for the UK press."
Specialists said today identical twins' DNA is just that - identical - although fingerprints may vary along with retina patterns.
"Are we dealing with a criminal genius here or is this standard MI6 smoke 'n' mirrors?" fabled cryptologist Prof Einstein Flintstone asked this afternoon.
The wall of silence is deafening.