Explosions

Question 1

What to look for

Answer 1

Characteristic damage caused by explosives includes:
- cratering
- spread of debris
- shredding of materials
- a smell peculiar to the exploded material; for example, the smell of almonds is often associated with explosive or exploded material
- an overlay of dust
- shrapnel marks.

Explosions caused by gas generally cover a wider area than those cause by explosives, and they do not leave a crater. Lighter-than-air gases such as hydrogen will create an outward blow at the top of a wall, whereas heavier-than-air gases blow out at the bottom of a wall. There are a number of other tell-tale signs, inclding the implosion of cabinets, which will be obvious to the expert.

There may also be medical evidence that one or more of the suspects or victims have inhaled gas prior to the explosion.

Question 2

Containers

Answer 2

You may find pieces of the device’s container scattered a considerable distance from the explosion centre.

Question 3

Non-electric detonators

Answer 3

Whether traces of the detonator remain will depend on how far it was placed into the explosive. If it was inserted well into the explosive, you are likely to find traces of the fuse only. If the detonator was not well inserted, you may find fragments of the detonator itself.

Question 4

Electric detonators

Answer 4

You may find:
- lead wire, which may help identify the type of detonator used - the remaining wire is often referred to as ‘fly wire’
- the neoprene plug
- the short-circuiting shunt - a small piece of plastic that is removed from the wires before they are connected intot he circuit
- the ‘delay setting’ tag from the lead wire
- fragments of the electric detonator casing (although this is highly unlikely).

Question 5

Safety fuses

Answer 5

Burning leaves most of the fuse in a limp state but you should still be able to identify the colour and manufacturer. The explosion may blow the fuse off its original path. You can find this path by looking for the scorched trail left by the fuse from the point of ignition to the explosion centre. This will be evident even on concrete, and may leave patches of a tarry substance.

Question 6

Detonating cord

Answer 6

Used detonating cord generally leaves little residual trace, but the surfaces over which it was laid may be damaged. You may find ‘cut off’ pieces of cord that have not detonated because, for example, they have been laid at sharp angles.

Also be aware that upon excavation trailers may still be located under debris that has fallen as a result of the fire.

Question 7

Igniter cord

Answer 7

Igniter cord often contains a thin wire and leaves a black, charred, ash-like remnant. This remnant is less substantial than that of a safety fuse.

Question 8

Reminder

Answer 8

Encourage the IED operator to consider using a non-destructive method of making a device safe, or one that involves the least possible destruction. This will avoid destroying evidence contained in the device, such as tool marks, fingerprints, wrapping paper and components, which may greatly assist the investigation if examined intact.

Safety must, however, outweigh the preservation of evidence. Be guided by the operator about the feasibility of dismantling the device.

Consider having the operator record their initial assessment on video to record all item and placements prior toany subsequent action by them. This can be used both evidentially and for staff briefings.