An Unusual Case of Identification of Transferred Fibres

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  • J. Forens. Sci. Sac. (1979), 19, 23 Received 13 December, 1978

    An Unusual Case of Identification of Transferred Fibres

    E. J. MITCHELL Home Ofice Forensic Science Laboratory, Sandbeck Way,

    Wetherby, West I'orkshire LS22 4DN and

    D. HOLLAND Detective Superintendent, West Yorkshire Metropolitan Police,

    Castlegate, Huddersjield, West Yorkshire HD1 2NJ

    A homicide case is described in which the identijcation of carpet fibres recovered from the body and clothing of a deceased boy resulted in the detection of the assailant, and the value of close collaboration of the police with the forensic science service is demonstrated.

    At approximately 7.30 p.m. on Thursday, 11 November, 1976, an 1 l-year- old boy dressed in scouts uniform left home to walk one and a quarter miles to attend the weekly meeting at the local scout headquarters. When he failed to return home a t the expected time of 9.30 p.m. his parents made enquiries and ascertained that he never arrived at the scout meeting. Senior scouts immedi- ately began a search and a t 11.20 p.m. on the same date the matter was reported to the police. On this night the area was shrouded in thick fog with a maxi- mum visibility of 40 yards, and at times much less. Throughout the night and the following day enquiries were made in the area and a search of the route was undertaken by a police task force. Full circulations were made in the press and on local radio but nothing came to light. A mobile police control post was established near the boy's home.

    O n the following Saturday his body was found by four university students in a ditch adjoining a lay-by beside a relatively isolated road in rural countryside several miles from his home. Only one student touched the body to ascertain that he was dead. The others went to summon assistance, and in due course both authors attended the scene of crime.

    The body was found lying partly on its side in a crouched position, and the trousers were slightly lowered to reveal the lower back. Superficial fibres were recovered by sellotaping the clothing and exposed body surfaces, and together with other items were examined at the Harrogate Forensic Science Laboratory. The Harrogate Laboratory was subsequently united with the Newcastle Laboratorv to form the Wetherbv Forensic Science Laboratorv. Semen was found in the boy's anus and inside the back of his trousers and underpants; some of the seminal staining was found to contain group A secretor substance. The boy's blood was group 0.

    An incident room was set up at Bradford Police Headquarters, which was near the boy's home, and a mobile control point at Yeadon near the place where the body was found. House to house enquiries were made and 5,320 questionnaires completed at Bradford and 530 a t Yeadon. 3,847 houses were visited. 9,954 school children were questioned by the same team of police officers, whilst another team of officers set out to visit each Bradford scout troop and question the members. During the subsequent enquiries a total of 5,301 statements were taken and a total of 9,187 persons were interviewed and eliminated.

  • I t was realised that only two clues were likely to lead to an arrest; the identification of the fibres on the body, and enquiries in the homosexual community of Bradford and the surrounding area.

    Extensive enquiries were effected into the homosexual aspect, but no-one was traced who had had any connection with him. In fact when the accused was subsequently traced, no previous links with the boy prior to the night of the attack could be found.

    Amongst the superficial fibres recovered from the body and clothing of the boy were over 200 man-made fibres which were similar in appearance. These fibres were of uniform short length, broad diameter, and were present as three separate colours; grey, mid blue and deep blue. I t was noted that, owing largely to the delustrant present, both types of blue fibres appeared dark when viewed by transmitted light and thus gave the impression that they had been shed by a dark coloured, or black, fabric. Incident light microscopy produced a more accurate record of the colours of the fibres and was confirmed in due course as more suitable in determining the correct colour of the parent fabric.

    The wide distribution of these particular fibres on the clothing and exposed body surfaces implied that the body had lain recently on a fabric from which the fibres were readily shed and, from the diameter of the fibres, the fabric was some form of carpeting. Further examination of a selection of recovered fibres identified them as nylon 66, fully delustered, approximately 2.5mm long, with a round cross section, the diameter of which corresponded to 17-22 decitex. The similarity in length of the fibres suggested that they had been cut from continuous filament fibre by a process known as flock-cutting, or flocking, for use in the flock carpet industry.

    Since the fibres were of an unusual type and were present in significantly large numbers, and taking into account the nature of the crime, it was decided that an attempt to trace the manufacturer would be worthwhile. Two lines of enquiry were made. Police enquiries were directed mainly a t carpet manu- facturers and major trade outlets, and a nationwide list of those engaged in flock carpet manufacture was prepared. Laboratory enquiries were directed towards a closer identification of the fibres themselves, in an attempt to identify the source of the nylon filament, and a number of major nylon producers were contacted for their advice and assistance. In addition, some of the recovered fibres were sent to the Home Office Central Research Establishment at Alder- maston. I t was found that in the manufacture of certain synthetic fibres, markers may be introduced to enable fibres to be subsequently identified to their producer. The amount of marker introduced initially, however, is small and is reduced during subsequent processing. Identification of the manu- facturer by this means from small quantities of fibre is usually difficult. As an alternative a list of possible fibre producers was prepared using the following characters found in the recovered fibres: nylon 66, round cross section, fully delustered, 17-22 decitex. Special regard was paid to producers of continuous filament fibre for the flock fibre industry.

    Both lines of enquiry established that the flock carpet industry was not large, and that many manufacturers could be eliminated as their flock fibre production was of a different length, thickness or colour. A few manufacturers were associated with the car industry, and the close similarity in length and thickness of the recovered fibres to those used in flock carpeting made specifically for some car manufacturers, together with the probability that the boy had been dumped from a vehicle, suggested initially that the fibres had been shed from a car carpet which had been fitted to a car during its production. However, whilst flock carpeting used in cars was black or, occasionally other colours, none supplied to car manufacturers could be found which contained all three colours of fibre recovered from the boy. Certain models of Triumph motor cars were fitted with nylon flock carpet in various colours and the police traced and checked a large number, in each case taping the carpet to pick up samples of

  • the loose fibres shed. None of these samples matched all those colours recovered from the bov.

    After a short period police enquiries centred on one particular firm, Flotex Limited of Derby. I n addition to manufacturing flock carpet for car floors, Flotex also made a range of flock carpets in standard colours for industrial and commercial use. One of these, coloured dark blue and brand-named Nuit, was made from a mixture of three colours similar to, and in approximately the same proportions as, the recovered fibres. Figure 1 shows a section through a piece of Nuit carpet.

    Flotex, which had been established in the early seventies, operated under licence from a French company, and had from the start imported continuous filament nylon 66 from Rhone-Poulenc-Textile in France. Comparison of the characters of the recovered fibres with those from other producers in the mean- time had indicated that the fibres were not of United Kingdom origin. A selection of recovered fibres were sent to Rhone-Poulenc-Textile who confirmed that in their opinion the fibres had originated in continuous filament form from them. Since enquiries made to other manufacturers in the meantime had not resulted in positive identification of the recovered fibres, the likelihood that they had come from another source was considered small, and it was therefore assumed that these had been shed from a Nuit carpet. This brand of carpet was re-named Peacock and marketed under the Flotex brand name until it was discontinued in June 1976, but prior to that date over 43,000 metres had been made at Derby. The great majority of this had been sold in large consignments to contractors, but it was known that odd lengths such as remainders or surplus production were sold through the factory shop and that, in some cases, this was bought by car dealers for refurbishing second-hand cars. I t was fortunate that Flotex had kept well-documented production and stock records, which facili- tated the police in identifying the distribution and end use of the total production of Peacock carpeting. The Police District Task Force of 50 officers were sent to Derbyshire where they went through all the order forms held by the firm and extracted those for the Nuit/Peacock range. Every order was followed up and

    Figure 1. Section through a flock carpet showing the backing, adhesive and fibre layers.

  • an attempt made to trace approximately 32 miles of carpet. I n each case the intention was to interview the carpet fitter and asccrtain what had happened to the off-cuts, as there was every likelihood of these having been fitted to a car.

    As a result of enquiries it was ascertained that a firm of floor covering specialists in Sheffield had received a consignment of Flotex, Peacock colour, for use in an office at Calverley near Bradford. Enquiries revealed that the carpet fitter had been given the off-cuts, totalling three square yards in area, and he had recovered the floor of his car with it. He had subsequently sold the car to a student living in Leeds. Thc car was traced and it was found that the student was studying at Bradford College to take a diploma in higher education. Bradford College is situated on the same street as the local scout headquarters.

    The suspect was interviewed some two months after the body was found and his car traced and examined. The Flotex carpet was still fitted. A written witness statement was obtained from him and routine blood and saliva samples were taken by the local police surgeon. When it was confirmed that the suspect was a group A secretor his motor vchicle was conveyed to the Forensic Science Laboratory on a low-loader type trailer, a procedure which ensures that forensic scientists receive a vehicle for thorough examination with the least possible contamination from unconnected sources. All the suspect's clothing was seized, after which he was interviewed at some length.

    At the time of the suspect being arrested, of the 43,000 linear metres of carpet manufactured, 20,000 linear metres had been traced and evidence of the whereabouts of another 8,500 linear mctrcs was known. From 3,509 vehicles examined only 15 were fitted with Flotex Nuit/Peacock carpeting and 13 were eventually eliminated. One vehicle was owned by the eventual defendant and one had been stolen and has never been recovered.

    The suspect when first questioned denied his involvement in the crime, and the length of time which had elapsed since the crime made it difficult to check his alibi and to determine which of his clothing he would have been wearing at the time. The suspect's blood group indicated that he could have shed the semen found on the boy's clothing. One of the suspect's pairs of trousers was made mainly from wool, together with a mixture of other synthetic fibres including nylon. The trousers were well worn and clearly demonstrated the abrasive nature of some of the stronger synthetic fibres in the mixture which, whilst still themselves comparatively intact, had sloughed off many of the wool fibres. The finding on the boy of a significant number of yellow wool fibres, but few others, matching thosc of the trousers from the suspect, was entirely consistent with the wool fibres having come from the trousers whilst being worn by the suspect at the time of the offence. I n addition some two dozen red cotton and viscose rayon fibres were recovered from the boy which matched a red towel in the suspect's possession, and which was believed to have been in the car at the time of the offence.

    The suspect was re-interviewed and eventually made a full confession to killing the boy. At Leeds Crown Court hc was found guilty of manslaughter, and sentenced to a term of seven years imprisonment.

    Acknowledgements The authors wish to acknowledge the assistance given by Mr. G. E. Coop

    and his colleagues of I.C.I. Limited (Fibres Division), Harrogate; Mr. J. A. Imlach of Rhodia (U.K.) Limited; Monsieur P. Hantzer of Rhone-Poulenc- Textile and Messrs. N. Simpson and J. Woollard of Flotex (U.K.) Limited, Codnorgate Industrial Estate, Derbyshire.

    Both authors wish to record the major part in the case played by the late Detective Chief Superintendent D. Hoban, whose tragic death occurred before