After a bombing has taken place, one of the first things that the police and security services will do is track down exactly where the improvised explosives devices involved in an attack were made.

David Videcette, a lead detective on Operation Theseus, the police investigation into 7/7 London bombings, has written a novel based on his experiences, The Theseus Paradox and he explains just how it’s done.

An odd use of premises can give away vital clues, as David explains, “Most people have a routine – they sleep, eat, go to work, have people visit in daytime hours. Bomb factories are often residential homes that are used like industrial premises.  People come to work there during the day and then leave in the evening. The bomb manufacturers don’t sleep in them. That would be far too dangerous because of the toxic fumes and in case the whole place goes up. And if nobody is sleeping there, that is the big giveaway. If the daily rhythms of visitors make it looks like a place of work and not a place of residence – why are they using a place of residence as a factory?”
David, who has written of his experiences of the July 2005 attacks in The Theseus Paradox, continues, “Chemicals used to create home-made explosive devices will usually have been ‘smelted down’ to make them more concentrated, just as they were in 7/7 and 21/7.  A key signifier of a bomb factory that we saw in 7/7 is bubbled paintwork from the intensive heat involved to make these chemicals more concentrated.  The bomb makers need premises with good ventilation, where windows can be opened and where face masks may well be used.”

During the preparation for 7/7, the extremists had to keep the windows of their bomb factory open to let out the toxic fumes.  To shield their bomb-making activities from prying eyes, they taped the curtains to window frames using masking tape so the wind didn’t blow them outwards. However, when these places are cleared and cleaned, evidence still remains.

David says, “As well as the odd use of premises, the purchase of brand new curtains is a big giveaway that something has been going on there.  In the 7/7 investigation, I came across one particular property and was concerned what it had been used for. When I visited, it was mainly empty but had new drapes and no net curtains. By spotting a tiny FRAGMENT of old masking tape attached to that window frame, I knew that something unusual had taken place there. They’d clearly been taping the old curtains to the window frame. We then hoovered the carpet and found enough explosive residue contained within one square metre to blow up the entire street!”

When toxic chemicals are ‘cooked’ there may well be tell-tale signs such as dying plants inside properties and outside of windows. 

David says, “Passers-by may have noticed odd smells and discoloured curtains or foliage. With the 7/7 bombers, it was noticed by their closest associates that some of the hair at the front of their heads had been bleached – we can see the significance of this now, but at the time witnesses didn’t pay much attention to it.”

Extensive locks fitted to normal entry doors and odd entry and exit routes will also be important, says David, and they will also need to consider power requirements.

“Heating the amounts of toxic chemicals required is very labour intensive and requires a great deal of power. There will have been excessive electricity use for the size of premises. In the 7/7 investigation, we found burnt plug and socket fittings and incidences where the electricity had ‘tripped’ again and again. We also found receipts for numerous ‘smelting vessels’, where the bottom of many, many pans had burned through.”

How do you go about tracking down these sorts of premises and persons involved?

“The security service will analyse data in an office capacity and the police will be looking at it from a witness and physical evidence point of view. The problem is the disconnect between the two methods. You need to use both together and have good communication between the two teams.  You can look at surges in power usage, call and contact pattern analysis (who has been in contact with whom), cell site analysis research – that’s looking at where their mobile phones were when they used them to talk or text - and they will want to question friends and family.”

David believes exhibits such as keys, in particular will be crucial.

“In 7/7, we took all the locks out of any premises we knew that the suspects were connected to and we matched the keys they had to the locks. That way, we could find out if they had keys for premises we hadn’t yet found. It may sound simple, but when you've got hundreds of keys and locks, it becomes a crucial part of the investigation.”

David considers the scene of devastation in Paris following the police raid on the suspected terrorist cell following the Bataclan attacks, “When you think about what happened in St. Denis, where police raided the premises of the suspected terrorists, finding anything of use there was unlikely after 5,000 bullet rounds and a series of grenades. But keys survive bomb blasts and bullets. I always say, look for the person with premise keys on them. They're highly likely to have been one of the most important people in that cell.”

The Theseus Paradox by David Videcette is available
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