The enigma of a code-breaker's death

The reputation of a brilliant man who served his country will be for ever tainted by the failure to explain his demise

CCTV footage of Gareth Williams at Holland Park Tube station (PA)

On Friday, in the Bethel Methodist Chapel in Angelsey, the funeral was held of Gareth Williams. In life, he was a mathematician and an encryption specialist so highly regarded that he was seconded from GCHQ in Cheltenham to work at MI6 in London. In death, he is an enigma, an infuriating mystery for most of us, a deeply upsetting puzzle to his parents; for, though his body is now laid to rest, the questions about the bizarre way he met his end show no sign of being buried. Yesterday brought another theory, something this saga has attracted as a September orchard does wasps.

The facts are these. Gareth Williams was 31, studied mathematics at Cambridge, was recruited by the government's listening and monitoring operation in Gloucestershire, and was lent for a year to MI6. He moved to London last September, lived in a five-storey security services safe house at 36 Alderney Street, Pimlico, worked on matters such as computer security involving the City, and led, as far as police can tell, a rather introverted existence – no known partners or lovers, and little socialising. His only enthusiasm beyond his work seems to have been cycling.

Last month, he took a holiday. He went to the United States, returned on 11 August, and was last seen alive on CCTV at Holland Park Tube station on 14 August, and shopping near Harrods the following day. Eight days later, when he failed to appear back at work, colleagues raised the alarm, and officers went to his home. His flat seemed undisturbed and unoccupied, but in the bath they found a red, outsized, zipped and padlocked North Face holdall. Inside were the decaying remains of Mr Williams. His body (he was 5ft 8in tall) was naked, curled up tightly, with his arms and legs contorted behind him. The bag had 140 litres of storage capacity, and was double-stitched. The flat's direct telephone link to MI6 had not been used, and its front door had been locked from the outside.

Subsequent tests have established that Mr Williams had not been drugged by any known substances and had not taken drink, and his body, the apartment and holdall showed no signs of a struggle. There were no scratches or bruises on his body. Initial examinations indicate that he died of suffocation, with dehydration contributing, but confirmation of this will have to wait for the results of two post-mortems, due in a fortnight's time.

As if these facts were not riddle or sensational enough in themselves, the speculation – by "sources" real or imagined, online or off – has added further layers of weirdness. Into the vacuum created by no swift explanation has rushed a large quantity of hot air and now discredited or denied theorising. He was a sado-masochist ("more James Bondage than James Bond", as The West Australian leeringly put it) with a flat full of porn and restraint equipment. Not true, say police. He had 12 gay lovers. Wrong again on several levels, apparently. He was poisoned "by a foreign power" or "terrorist group" (he had worked, briefly, on systems in both Northern Ireland and Afghanistan), possibly by being injected with polonium, the substance that did for Alexander Litvinenko. There is no evidence for this, either.

What has some credibility is the latest idea, floated by yesterday's Daily Mail, that "MI6 spook did not die alone". This was an answer to the stories that Mr Williams died as a result of a hazardous sex game, a form of auto-eroticism that involved him being able to confine himself in the holdall and then somehow close the zip and secure the padlock. A woman police officer had, according to previous reports emanating from the Mail group and others, re-enacted this scenario to a fully padlocked conclusion.

This theory, which left the locking of the front door from the outside somewhat unexplained, was now, however, pooh-poohed, and, according to the Mail, "He was padlocked into the bag by someone else... and was alive when he got into – or was forced into – the bag." Yet the sex game idea was not entirely abandoned, as it was now speculated that he may have been shut in the bag, his assistant (or assistants) locking it before departing the flat; they were due to return to release him but miscalculated and found him dead when they came back.

This line of thought, outré though it sounds, does lead back to the remaining known facts about Mr Williams' life in London. Both of them involve his association with a couple who have yet to be traced. It has been established, for instance, that, twice a week over a period of a few months, Mr Williams had gone to the Patisserie Valerie in Holland Park, ordered an americano and waited. After a while, a couple would appear, order nothing, talk to Mr Wiliams for some minutes and then leave. Then there is a couple, described as "of Mediterranean appearance" (which the couple in the café were not, eye-witnesses say), who had a key, or at least ready access to Mr Williams' MI6 flat. Neighbours say that this pair did not, as far as they casually observed, need to be "buzzed up" to the flat by Mr Williams.

And so the mystery now lies, doomed – unless clarity is achieved soon – to churn for ever in the articles and websites of conspiracy theorists, leaving the name and reputation of a brilliant man in the service of his country tainted by the failure to explain his death adequately.