Automotive flock and its significance in forensic fibre examinations Josephine Jones ⁎, Tiernan Coyle Contact Traces Ltd, The Centre for Innovation & Enterprise, Begbroke Science Park, Sandy Lane, Yarnton, Oxford, OX5 1PF, UK abstract article info Article history: Received 29 April 2009 Received in revised form 15 May 2009 Accepted 21 May 2009 Keywords: Trace evidence Vehicles Flock Fibres Microscopy FTIR Raman Discriminating power The interiors of fifty eight vehicles were examined and samples were taken. All vehicles had samples of flocked material in their interiors. Flocked material was found on the window channels, window frames, door edges and in glove compartments or central console compartments. The majority of flock fibres used in the vehicles examined were carbon black pigmented polyester or nylon. A variety of dyed nylon fibres were also used in the vehicles. The discrimination power of dyed flock fibres used in the interior of vehicles was found to be 0.974. The front seats of these vehicles were examined for loose flock fibres. All vehicles had flock fibres present on the front seats. In the majority of vehicles, flock originating from material in the vehicle's interior was present on the front seats of the vehicle. The number of flock fibres present on the front seats varied greatly from car to car but did not appear to be dependant on the type of seat fabric or on which areas in the car were flocked. © 2009 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved. 1. Introduction Over the last few years we have seen an increase in cases involving motor vehicles where flock fibres were found to provide an evidential link between clothing (from a suspect or victim) and the vehicle in question. This seems to occur more often in cases involving vehicles manufactured in the last 10 years. Although many studies have been carried out detailing fibre transfer from vehicles to items of clothing and vice versa [1,2], little known work has been carried out into examining the use of flock fibres inside vehicles. This study investigates the types of fibres used in flocked material and also where this material is found in vehicles. Comparisons of flock samples from different vehicles will help to establish the level of discrimina- tion of flock fibres and therefore assist in providing a basis for assessing the evidential significance of finding such fibres in a case. Flocked material is made by propelling short (0.5–4 mm) mono- filament fibres directly onto a substrate that has been previously coated with an adhesive. The process electrically charges the flock fibres, causing them to “stand-up” so that they stick into the adhesive at right angles to the substrate [3]. In vehicles, some applications of flocked material are in areas where fabric with a soft velvet-like feel is desirable or where sound insulation is required. Flock may also be produced as a yarn and woven into textiles. The main application of textiles woven with flocked yarn is for covers of car seats [4]. Since the fibres adhere to the surfaces of the adhesive, rather than penetrate or imbed in it, fibres are shed readily from the surface of flocked material. In a study carried out by Roux et al. [2] it was found that many fibres from the clothing worn by the driver of a vehicle were transferred to the surfaces of the seat even after a short lived contact. The simple action of sitting on a seat generated transfer of 100–10,000 fibres. This number was influenced by the kind of garment and the driving time. Therefore if there are fibres present on the seats at the time of contact, either from the seat material itself or a population of fibres (e.g flock), then when contact occurs with the seat, these fibres should be transferred back to the clothing of the recipient. Considering the high shedding ability of flocked material it is logical to suggest that during normal use of the vehicle these fibres should be continually deposited on other surfaces within the interior of the vehicle (e.g the front seats). If this is the case, there is no reason why flock fibres would not be transferred back to the recipient clothing, either in contact with the flocked material itself or indirectly via another surface (such as a seat) and therefore potentially provide a two-way transfer of fibres between the interior of the vehicle and the clothing in question. Wiggins et al. [5] stated: “When a two-way transfer of fibres has been established, there can be little doubt that contact has occurred”. In that study two types of car seat fibres were targeted and looked for on over fifty garments. When targeting a “rare” type of black polyester used in only one vehicle model for a short period of time, no such fibres were found at random on the clothes targeted. Only one grey polyester fibre from a “common” fabric type was found at random. This suggests that regardless of the number of potential sources for a particular fibre type, Science and Justice 50 (2010) 77–85 ⁎ Corresponding author. E-mail address: josephine.jones@ContactTraces.com (J. Jones). 1355-0306/$ – see front matter © 2009 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.scijus.2009.05.003 Contents lists available at ScienceDirect Science and Justice journal homepage: www.elsevier.com/locate/scijus