Damage to Textiles
Contributed by Sandy Koch
A fabric damage analysis starts with characterizing the type of fabric of the textile and combines an analyst’s knowledge of how different weapons or objects typically produce damage with test cuts/punctures/shots made in an undamaged portion of the garment using the suspected weapons.
These tests may provide information either corroborating or refuting a scenario, information about the potential implement that was used to cause the damage and how the damage may have been caused (single insertion, cuts with associated tears, etc). Textiles may be woven, knit, nonwoven or a combination of these. A thorough understanding of how these textiles are constructed and how different weapons affect each particular type of fabric is necessary, especially in cases where a cut/tear crosses a seam. Test cuts or damage should be conducted during training in order to recognize the variation of damage that may be produced by different weapons as well as through normal wear. Hospital cuts and scissor stop marks which are typical in gunshot and stabbing cases must be recognized and noted but are generally excluded from a fabric damage examination. Photography of the item prior to conducting any analyses is necessary in order to provide documentation of the original condition the garment was received in prior to analysis. Other evidence (hair, blood, paint, etc.) which may require additional analysis should be documented and removed. The physical damage should be documented prior to conducting test cuts for dimensions (size, length, diameter, etc.) of any damage and the presence of the characteristic V shaped notch indicating a single edged blade.
Do not alter the condition of a questioned specimen (e.g., shape, position, layers or relation of one yarn to another) before photographic documentation has been taken.
An evidentiary weapon or other specimen (e.g., a piece of fabric, knife, screwdriver, etc.) should never be brought in contact with the known fabric from which it is suspected to have originated or damaged until all other forensic analyses ( DNA , latent fingerprints, toolmark analysis, etc) have been performed on the questioned specimen and weapon.
Repetition can mitigate the chances of missing tangential details, such as biological contamination (blood, semen and saliva, for example) and other trace evidence (hair, paint chips and fibres, for example), which may be trapped within the rope strands or the knots themselves. Knotted evidence should never be untied, unless there are specific forensic or legal reasons for doing so – such as searching for possible DNA or trace evidence – and that process must be recorded under controlled conditions and only after the knots have be clearly photographed and accurately identified.
Cuts and tears in fabrics can offer a great deal of information. Test cuts may be made with possible weapons to see if they make cuts or tears consistent in the shape and length found on the evidence. These test cuts should be made in an undamaged portion of the item or if it is too damaged then in a similar type of fabric. Test surfaces to lay the fabric over can vary between a cardboard box to gel molds to high end body replicas often used in bloodstain analysis. In addition to comparing the test cuts to cut/tears found in evidence, the relative position of a knife in relation to the cut mark may be determined if a single edged blade was used and the characteristic “v” shaped notch is found at one end of the cut/tear mark.
Weapons should be searched for fibers like the fibers comprising the damaged garments. Should a fiber association be made, it can strengthen a cut/tear conclusion though the report language for the fabric damage should still be limited to consistent in size and shape with the test cuts and consistent with having been made by that weapon or other implement with similar characteristics (size, shape, sharpness, etc.).
1. Kemp, S.E., D.J. Carr, J. Kieser, B.E. Niven and M.C. Taylor “Forensic evidence in apparel fabrics due to stab events” Forensic Science International 191(2009)86-96.
2. Hearle, J.W.S., Lomas, B., Cooke, W.D. and Duerden, I.J., Fibre failure and wear of materials - An atlas of fracture, fatigue and durability. New York, NY: John Wiley and Sons, Inc., 1989.
3. Dictionary of Fiber and Textile Technology. Charlotte, NC: Hoechst-Celanese Corporation. 1990.
4. Taupin, J.M., F.P. Adolf and J. Robertson “Examination of Damage to Textiles” in Forensic Examination of Fibres 2nd edition. Edited by J. Robertson and M. Grieve, 1996.