The compelling case of MI6 spy Gareth Williams, found dead and padlocked in a bag in 2010, is yet to be solved. A veteran army officer demonstrated how Williams could have zipped himself inside the sports bag without any help and perhaps been suffocated to death.

A retired sergeant in the Royal Artillery, Jim Fetherstonhaugh, 49, says it is not only highly possible that Williams locked himself in the bag without any aid, but it is also a very simple and easy task to perform (including padlocking oneself).

Many MI6 agents, after Williams' death, tried more than 300 times to lock themselves up in similar sports bags but failed.

The man on TV tried it 300 times and I was amazed he couldn't do it. I've told my friends and show them and their jaws drops - it is so obvious, maybe people are thinking too much into it, Fetherstonhaugh said.

But the army veteran claims to have discovered a way in which one can get inside a bag, zip it and even lock it with a padlock, without any assistance.

The technique discovered by Fetherstonhaugh is apparently the reverse of a popular trick used by airport thieves to steal from locked bags as long as they are flexible and the sides can be pinched together, reports Mail

Fetherstonhaugh, after discovering this method, called the police but has got not any response yet.

The ex-army sergeant was intrigued ever since Williams' mysterious circumstances of death hit headlines. To examine his theory, he asked his 16-year-old daughter Izzy to climb inside a similar North Face bag without any assistance.

Izzy, who stands 5ft 5ins (3ins shorter than Gareth) managed to easily fit inside the bag. She could not only draw the zip together but was also able to padlock herself.

The procedure can be carried out much more easily in a bathtub, since the occupant can push against the sides of the tub for assistance.

According to Fetherstonhaugh, when one is in a foetal position in the bag, the height of a person does not make too much of a difference, so the fact that Williams was 3 ins taller than Izzy wouldn't matter much.

She is 5ft 5 and he was 5ft 8 but when you're in the foetal position inside that height doesn't make much difference. She had a bit of a struggle pulling the bag but she wouldn't have been as strong as him. I could easily see that he would be able to do it, the army veteran said.

Now the question arises as to why the experts were unable to do the same. It seems, according to experts, there wasn't enough room to manoeuvre when the bag was kept in the bathtub.

It has been two years since Williams' death and despite extensive investigation, the case does not seem to be getting anywhere.

Police believe that at the time of the 31-year-old's death, a member of either MI6 or GCHQ was in the flat.

At the inquest, coroner Fiona Wilcox told Westministers coroner's court that it was highly unlikely that Williams got inside the red holdhall on his own.

There are no foot or fingerprints from the scene of death and fifteen of Williams' colleagues have already been swabbed for DNA samples.

In a recent development in the case, a green towel from a shelf in Williams's kitchen with traces of human residue was found. It could lead to a breakthrough in the case.

Williams' former landlords had reported of an incident at the inquest about how William had once handcuffed himself to a bed alone and needed assistance to free himself later. This points to a possible fetish for restraint that Williams might have harbored.