28 August 2010 Last updated at 07:22 ET

Tests on dead MI6 man Gareth Williams 'to take days'

Mr Williams was last seen eight days before he was found dead

Investigators are several days from discovering what killed an MI6 worker found dead in his London flat, police have said.

Gareth Williams, 30, from Anglesey, was found in a holdall in the bath of his home in Pimlico on Monday.

A post-mortem examination was inconclusive, and complex tests could carry on into late next week.

Officers are trying to find out whether Mr Williams was asphyxiated or poisoned and if he had taken drugs or alcohol.

Police have said that Mr Williams was in London from 11 August and that the last sighting of him was on 15 August.

They have refused to confirm the nature of the sighting.

Mr Williams' family has issued a statement which said: "Gareth was a generous, loving son, brother, and friend, and he was a very private person.

"He was a great athlete, and loved cycling and music. His loss has devastated us and we would ask that anyone with information come forward and assist the police enquiry."

The Metropolitan Police has not classified his death as murder but is treating it as "suspicious and unexplained".

Mr Williams, a keen cyclist, was on secondment to MI6 from his communications officer's role at GCHQ.

A brilliant mathematician, he graduated with a first class degree in maths from Bangor University aged 17.