Police investigating the death of MI6 worker Gareth Williams are appealing for help to trace two people seen entering his central London flat earlier in the Summer.
CCTV footage showing him shopping in London has also been released as Scotland Yard appeal for anyone who saw the 30-year-old, in the days before his body was found, to come forward.
Officers are keen to get in touch with a couple who may have visited Mr. Williams in late June or early July.
The couple are described as both being of a Mediterranean appearance and between 20 and 30 years old.
They were seen going in through the communal door of the property in Alderney Street late one evening.
Police were called to Mr. Williams flat in Pimlico after colleagues working at the nearby MI6 riverside building raised concerns that he had not been seen for “some time”.
He had been on secondment at the secret service headquarters from his job as as a communications officer at GCHQ in Cheltenham, fuelling speculation that he may have been killed by a foreign agency.
It has emerged that Mr. Williams had returned to the UK from a planned holiday in the USA shortly before he died.
Mr Williams, from Anglesey, was found unclothed, in a zipped and padlocked red North Face holdall, which was in an empty bath in the ensuite bathroom of his London flat on the 23 August.
It was originally believed that the MI6 worker could have been dead in his flat for up to two weeks – but CCTV footage shows Mr. Williams shopping in the West End and Knightsbridge areas on the 14 and 15 August – eight days before police entered his the flat on Alderny road.
Officers from the Homicide and Serious Crime Command said Mr Williams, who returned to the UK on Wednesday 11 August, was caught on CCTV cameras shortly before his death.
They are appealing for any witnesses who saw him from 11 August to the 23 to come forward.
CCTV images show Mr. Williams entering the Holland Park underground station on Saturday 14 August and shopping in Brompton Road on Sunday 15 August.
Det Ch Insp Jacqueline Sebire said: “This remains a complex unexplained death enquiry,
“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.”
A mobile phone and several sim cards were found near Mr. Williams body but officers today said there was no suggestion the items within the flat were specifically posed.
Scotland Yard say, following extensive forensic examinations of the flat, there is also no evidence of property having gone missing from the premises.
Officers have said that initial indications from toxicology examinations show no trace of any alcohol or routine or recreational drugs.
An initial post mortem proved inconclusive as to cause of death. Testing for any other substances continues.