Police investigating the death of British code-breaker Gareth Williams have appealed for help in tracing two people seen near his Government flat.
Scotland Yard want to identify a man and a woman, both of Mediterranean appearance and aged between 20 and 30, who were let into the communal entrance of Mr Williams' flat in Pimlico, central London, late one evening in June or July.
His decomposing naked body was found padlocked shut in a holdall in a bath on the top floor flat by officers who broke in on August 23 after Mr Williams failed to appear at work for several days.
Officers have also released CCTV footage of him as they appealed for the public's help. It showed the 30-year-old entering Holland Park Underground station at about 3pm on Saturday August 14.
Police said post-mortem examinations found "no obvious cause of death" and initial indications from toxicology tests showed no trace of any alcohol or drugs. Testing for other substances is ongoing.
Detective Chief Inspector Jacqueline Sebire, who is leading the inquiry for the force's homicide and serious crime command, said: "I would appeal to anyone who may have seen, or had contact with Gareth in the period between 11th and 23rd August to come forward and speak with us. This remains a complex unexplained death inquiry."