Forensic Fibre Analysis - "Truth is smaller than fiction"

Article taken from Issue 1 of the Forensic Access Newsletter "Benchmark"

Amongst the most rewarding cases forensic scientists can get involved with are those where their findings provide clear support for one side or the other and therefore help the Court reach a verdict.

One such concerned a man accused of strangling his wife after a party held at their house. The man said that he had found her dead in bed the following morning - he had spent the night asleep in front of the television. He pointed the finger at someone else - another man who had been a guest at the party.

A large number of items including bedding, and clothing variously from the dead woman, her husband and the other man were subjected to a detailed scientific examination. Various things were found during the course of this but none which might help to establish which, if either of the two men might have been the guilty party.

It was at this point that we were approached by the husband's solicitors. Essentially they wanted to know whether there was anything at all in the scientific line which might support what their client was telling them.

We started by getting to grips with the circumstances, and which indicated that whoever had killed the woman must have been in prolonged physical contact with her. This immediately meant that there was a good chance that textile fibres would have been exchanged between the clothes they had each been wearing at the time, and the bedding on which the killing seemed to have occurred.

Such exchange would not have meant much so far as the husband was concerned because fibres from him would be expected to be found all over the house in the normal course. But the same was not true of the other man. In particular, there was, apparently, no cause for him ever to have visited the dead woman's bedroom.

We established that this man had been wearing two fairly distinctive items of upper clothing which, together, were composed of a number of different types and colours of textile fibres. We searched painstakingly for each of these amongst surface debris removed from the dead woman's body, clothes and bedding.

Painstakingly is the word. The sort of fibres we are talking about are not strands of yarn, but individual filaments which make up such strands. They are not readily visible to the naked eye but have to be magnified up to 400 times normal size to be seen properly, and for their precise colour, cross section and detailed internal features to be made out. Finding them in amongst a myriad of others of assorted sizes and colours that tend to collect on surfaces such as clothing and bedding is an art in itself, and manipulating and analysing them, another art.

In any event, we found a substantial number of these - more than might be expected if they had been transferred secondarily to the woman's clothing and her bedding via something else. All this served to cast serious doubt on whether the right man was in the dock. This seems not to have been lost on the jury and the woman's husband was promptly acquitted.