Gareth Williams, 31, was found dead in his home in Pimlico, London in 2010
His body was found naked and decomposing in a padlocked red North Face bag
Strand of hair was found on Williams hand but DNA profile couldn t be extracted
But advances now mean profile could be taken from just a tiny sample of hair
Forensic expert Professor Angela Gallop suggested case should be rexamined
Spy in the Bag died in kinky sex game and NOT Russian hit: Detective who led probe into death of MI6 agent rules out Moscow assassination - and says answer lies in his private life as he leads calls to reopen investigation
Retired lead detective believes Gareth Williams was not killed by Russian state
Williams, 31, was found dead in his home in Pimlico, London in August 2010
His decomposing body was found in a padlocked red North Face sports bag
Coroner ruled it was unlawful killing but police said he got into the bag himself