This lecture is an introduction to the damages done to textile fibres and how these damages can help in criminal investigations.

1. Damage to
Textiles

3. Value of damage evidence

4. Types of cases where
damage analysis could be
invaluable
Any crime where clothing or textiles may be
damaged such as
• homicide or suicide
• rape
• sexual assault
• armed robbery.

5. Use of damage
information
• Provide information about the possible implement that
caused the damage
• Provide information about the manner in which it was
caused- crime reconstruction
• Damage analysis may corroborate or refute a particular
crime scenario.
– Especially important in suspected false reports of rape
and assault.

6. Hypotheses
• Often cases involve two
competing explanations for
the cause of the 'evidence'
damage:
– those provided by the
prosecution
AND
– Those provided by the
defense.

7. Testing the
hypotheses
Three considerations when testing the hypotheses:
• Results of previous research
• The 'principle' that damage characteristics will reflect
their cause,
• The use of simulation experiments

8. Using a simulation
(a case)
• An American soldier stationed in Ramstein, Germany, was found
murdered in a road works area.
• The man had bled to death and was wearing a 'bomber jacket'.
• The cloth of the jacket was damaged in the area between the
shoulder blades
• A crowbar was collected close to the body which was initially
suspected to be the murder weapon.

9. • Control damage was performed in the outer fabric with the pyramidal top
of the crowbar.
• Comparing the characteristics of the simulation damage with the crime
damage demonstrated that the source of the damage in the jacket could
not be the crowbar (neither pyramidal top or the blunt end).
• The examination showed that a two-edged stabbing device must have
been used.
• Further investigation revealed that a comrade of the deceased had a two-
edged knife in his locker.
• Blood on this knife was found to match that of the deceased.

10. Damage-
indicates weapon
• Characteristics of the damage may indicate the type of
weapon used.
• This may assist the investigator:
– search for the suspect weapon or
– Include or exclude a particular weapon for comparison.
• The more distinctive the weapon and the more outstanding
the characteristics in the damaged textile, the stronger is the
link between the weapon and the damage.

11. • Damage to textile shows more details than
associated wound and therefore more
effective in linking weapon esp. in cases of
decomposition of body.

12. Categories of
textile damage
Three broad categories of events may cause damage to textiles:
• mechanical effects,
• chemical effects and
• the influence of heat.
– Damage may range from minor, such as slight scorching, to
combustion.

13. Mechanical
damage
• Damage by normal wear and tear
Includes:
– unravelling of hems, seams,
– snags (especially in stockings),
– pilling
– the thinning of fabric prior to the formation of holes

14. • Tear: A severance caused by the pulling apart of a material,
leaving ragged or irregular edges
• Cut: A severance with neat edges produced by a sharp-edged
instrument.
Types of cut
• Stab-cut
– Most often produced by a knife.
– Variables affecting profile include the elasticity of the fabric,
the sharpness of the knife blade, the angle of the blade to the
surface

15. • Scissor-cut:
– Indicated by the presence of 'stoppages' or small 'steps'
produced by the opening and closing action of scissors as they
are cutting along material
• Slash-cut:
– Generally produced by a sharp-edged tool (knife, razor blade,
scalpel, etc.) in a slashing motion with a start and finish 'point’.
– May not penetrate the material completely or may penetrate
intermittently, i.e. the cuts are not continuous.

16. Scissor cut with stoppage

17. • Puncture:
– Penetration through material by an implement producing an
irregular hole.
• Abrasive damage:
– Caused by the material rubbing against another surface.
– May result in the thinning of the material, even holes and
fraying

18. Abrasion

19. • Tensile failure:
– Fracture of the textile through pressure, especially in ropes.
• Animal damage:
– Bite marks and other severances produced through the jaws
and feet of an animal (canine, dog, mouse, rat, etc.).
– Insects such as moths and carpet beetles may ingest
the fibres, producing small puncture-like holes

20. • Microbial damage: This is irregular damage to material,
most often seen in burials. Microbes such as bacteria and
fungi may destroy fibres.
– Occurs preferentially in natural fibres, on occasions
leaving synthetic material unaffected.

21. Types of
materials
• The construction and composition of the textile fabric or material
are pivotal in assessing and understanding damage characteristics.
– knowledge of the structure of the different kinds of textile
fabrics such as weaves, knits and nonwovens
– understanding of their mechanical and physical properties such
as elasticity.

22. • The damaged article should:
– first be classified according to its construction—weave,
knit, or non-woven.
– The yarn type should also be noted inclusive of the fibre
type.

23. Differentiating a cut from a
tear in woven textiles
Tearing Indicators:
• Damage follows preferred direction of tear- i.e. parallel to the warp
or weft.
• Associated stretching
• Edges devoid of 'planar array'
• Noticeable 'curling over' of the fabric along the severance line.

24. Tear in a woven Fabric

25. Tear vs cut in woven fabric

26. Cutting Indicators:
• No preferred direction.
• Relatively featureless edges.
• An ability to fibre-end or pattern match.
• Presence of a significant 'planar array'.

27. Differentiating a cut from a
tear in knits
Tearing Indicators:
Damage follows preferred direction of tear.
Associated stretching.
Distortion of fabric along the severance line.
Noticeable 'curling over' of the fabric along the severance

28. Cutting Indicators:
• No preferred direction—an ability to track in any direction.
• Discontinuities typical of scissor-cut 'stoppages'.
• Presence of tightly bound 'tufts/snippets' along the severed edge.
• Presence of a significant 'planar array'.

29. Non-woven Materials
and Leather
• The outer macroscopic characteristics of tears and cuts
usually are distinct in these types of materials:
– The edge lines of cuts are neat.
– The edge lines of tears are clearly ragged or fibrous.
• This is produced by the non-oriented structure of leather and non-
wovens which is not based on yarns but directly on fibres.

30. Fibre Damage
• https://www.youtube.com/watch?v=NWAadzckHCE
• https://slideplayer.com/slide/4135293/

31. Preservation and Handling of
Exhibits
• The textile should be photographed in situ before removal.
• Care should be exercised when removing the textile from the
crime scene or other environment so that any damage is not
altered.
• The textile should be carefully dried, preferably flat at room
temperature, to prevent the growth of bacteria and fungi.

32. Monitoring the History of the
Exhibit
• The history of the exhibit since it was damaged should be
documented,
• for example if it had been washed by the wearer.

33. Obtaining Background
Information
• Reports such as:
– Pathology reports,
– Victim statements and
– Circumstances of the 'crime' event

34. Recording Damage in
the Laboratory
• The 'original' appearance of the damage on the textile should be
photographed.
• Make case notes that are easily understood and comprehensive
• If a weapon is submitted this should be examined recording
length, breadth, thickness, sharpness and irregularity of the blade
and cutting edges.
• The removal of other evidence such as blood and fibres will be
necessary before any simulation experiments are made.

35. Three level textile
examination
Fabric level.
• The positioning, extent and profile of the damage should be noted
including severance lengths.
• Yarn level. The relative positions of the yarns along the severance
and the severed ends of the yarns themselves (neat or frayed) may
be important.
– This is probably the most informative level.
– Features such as planar array, nicks and steps should be
observed.

36. • Fibre level.
– While it should be noted, this level is less
valuable.

37. Simulations
• Generally, it is preferable to use an undamaged area of the case
garment for simulations,
• The garment may also need to be held under a certain tension or
have 'backing', depending on the scenario.
– The artificial flesh model of Heuse (1982)
– or a roll of pork

38. • Consideration should also be given to the person performing
the simulations.
– In some cases, it may be appropriate to select an individual
of comparative strength or other capability to the alleged
offender
• Matted and tangled fibres at the ends of cut yarns indicate that
the garment has been washed.
• If the fibres are still completely 'in line', this indicates that the
garment has not been worn to any great extent since being
damaged.

39. Interpretation
and
Limitations
The interpretation of the findings of an
examination of damage to textiles should
result in:
• the determination of the type of damage
(tear, cut, etc.).
• the class of weapon should be
determined -if the source of the damage
can be related to a weapon, (single-edge
knife, screwdriver, etc.).

40. Limitations
• There will always be difficulty in
attempting to simulate a scenario.
• The damage may be governed by a
number of variables which are
unknown or which cannot be
replicated:
– the body weight and type of the individuals
involved,
– their movement
– the angle and type of thrust
– position of the clothing.

41. • The interpretation of damage may be seriously limited if
further damage not associated with the offence is present
and the required background information is not forthcoming.
– This typically occurs in removing clothes from the victim, such as
cutting off clothes with scissors at a hospital or 'tearing' of damaged
clothes