Fibres provide key to fatal car crash case

Most of what the fibres department does at Huntingdon s Forensic Science lab is at the forefront of technology, but some of it is surprisingly low tech. Adhesive tape is used to lift fibres from the seat of a car, for example. One dramatic case solved by

Most of what the fibres department does at Huntingdon's Forensic Science lab is at the forefront of technology, but some of it is surprisingly low tech. Adhesive tape is used to lift fibres from the seat of a car, for example.

One dramatic case solved by looking at fibres was a fatal car crash near Ely.

The story is told by Will Hutchinson, who works with fibres at the lab, as well as lecturing at Nottingham Trent University. "Two cousins were in a car that crashed at speed into a tree. They were both thrown from the car but one guy died and the other was unharmed and he said 'I wasn't the driver'.

"The car had been going so fast that on impact, fibres from the two men's clothes had been impaled in the plastic dashboard. Also, the plastic from the dashboard had melted into the fabric of the men's trousers.

"Neither of the men was wearing anything on their upper body. It was a hot day. Both of them were wearing jeans and the plastic had melted into the fabric. Polymer melts at 250 degrees.

"Denim is usually a difficult material to isolate because it is dyed with indigo, a natural product and because it is so common - everyone has denim, but in this case one man was wearing light blue jeans and the other dark blue."

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Examination of the fibres embedded in the dashboard on the driver's side showed that the survivor had been the driver. He had previous similar offences and was sent to prison for more than 10 years.

It is a cruel irony that the impact on his passenger, the dead man, had been in the groin, which was extensively damaged and provided some grisly photographs. Potential boy racers - take note.

Looking at fibres through a microscope is a long, laborious and painstaking process. There are six successive tests before it can be satisfactorily (if not conclusively) established that fibres from the scene match fibres from the clothes of a suspect or victim.

Fibres will be examined under a microscope using three different types of light, including ultra-violet and blue light, to match for colour. They are then examined to see what they are made of, and finally they are broken down to see if they are from the same batch of dye. This last test is regarded as the clincher, but it is left until last because the process destroys the evidence.

In an experiment just for me, Will barely touched the sleeve of my navy jacket with a yellow angora jumper. It was the merest touch and, to the naked eye, there was nothing to see on my sleeve. Then we looked at the sleeve under untra-violet light and I could see my arm covered in yellow fibres.

He said: "Timing is of the essence with fibres because they will start dropping off, the majority of them within the first couple of hours.

"If a balaclava has been worn for a robbery, the offender could say, 'yes, that is my balaclava, but I haven't worn it for three months.' However, if fibres from the hat are found in his hair, then it points to his having worn it in the last day or so."

With adhesive tape at one end of the technology scale in the fibres operation, at the other end is a hand-held microscope attached to a laptop. This is invaluable for taking to crime scenes, including car crashes - it being difficult to take a whole car into a lab for examination.

The best fabrics to wear while you are out committing a crime are undyed or ones that do not leave fibres, such as leather or rubber, says Will.

True, but it would be so difficult to be inconspicuous in that.

You would be hardly likely to merge into the crowd.

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