1. Forensic Identification of Hair

2. preface During the course of a criminal investigation, many
types of physical evidence are encountered. Hair
is one of the most common forms of trace
evidence that can be collected from a crime scene.

3. preface Hair grows everywhere on the external body
except for glabrous skin such as palm, feet, and
lips. It is easy to be pulled off by force and left on
the scene. In addition, hairs may naturally 'fall' out.
There are about hairs 'fall' out each day.

4. preface These hairs may be left on clothing or ground
unintentionally. All these characters make hairs so useful
as associative evidence in forensic science.
What clues can you get from the hair?
we will discuss the Biology of hair of human hair and what
part of hair is the focus of a forensic investigation.

5. Biology of hair 2. growth 3.physical properties 4.chemical properties
1.structure
2. growth
3.physical properties
4.chemical properties

6. Procedure of examination
1.Whether it is hair or not?
2.If hair, whether it is human or not?
3.If human’s hair, who left it ?

7. Biology of Hair composed of keratin(角蛋白)
produced from hair follicle(毛囊)
color --- pigments（色素）
appearance --- nutritional status
and intentional
alteration
Hair is composed of the protein keratin, which is also the primary component of finger and toe nails. Hair is produced from a structure called the hair follicle. Humans develop hair follicles during fetal development, and no new follicles are produced after birth Hair shape (round or oval) and texture (curly or straight) is influenced heavily by genes. Hair color is mostly the result of pigments, which are chemical compounds that reflect certain wavelengths of visible light. The physical appearance of hair can be affected by nutritional status and intentional alteration (heat curling, perms, straightening, etc

8. 一.Feature of hair Structure Shape & color Body area Growth
Physical and Chemical Properties

9. Hair structure Hair tip Hair shaft Skin Hair root Hair cuticle 毛小皮
Hair cortex
毛皮质
Hair medulla
毛髓质
Hair root

10. Hair shaft（毛干）
hair medulla
毛髓质
hair cortex
毛皮质
hair cuticle
毛小皮

11. Hair Structure Medulla-central core Hair is composed of three parts:
Cuticle –outer layer composed of overlapping scales
The structure of hair has been compared to that of a pencil with the medulla being the lead, the cortex being the wood and the cuticle being the paint on the outside.
Cortex--protein-rich structure around the medulla that contains pigment
Medulla-central core
(may be absent)

12. Morphology: Cuticle
Protective coating made of overlapping scales, produce a characteristic pattern
Not useful in individualizing human hair
Can be used for species identification

14. Morphology: Cortex
Made of spindle-shaped cells aligned in a regular array, parallel to the length of the hair
Embedded with pigment granules that give hair its color
The color, shape and distribution of the granules provide points for forensic comparison

15. Morphology: Medulla
canal like structure of cells that runs through the center of the cortex

16. Medullary Index
Measure of the diameter of the medulla relative to the diameter of the hair shaft
Usually expressed as a fraction
Humans: medullary index < 1/3
Animals: medullary index > 1/2

17. Medulla of Different Species

18. Forensic Analysis of Medulla
Presence of medulla varies quite a bit: even hair to hair
Human head hairs generally have no medulla or may be fragmented ones;
Most animals have medulla that is continuous or interrupted

19. Forensic Analysis of Medulla
The shape of the medulla can help identify a species
Examples:
Most animals and humans: cylindrical
Cats: pearl shape
Deer: spherical occupying whole hair shaft

20. Identification and Comparison of Hair
Morphological Characteristics do not allow individualization of a human hair to any single head or body
Hair when collected with an adequate number of standards can provide strong circumstantial evidence
Scale structure, medullary index, and medullary shape are most often used for hair comparison

21. Identification and Comparison of Hair
Evidential value lies with degree of probability associated with a questioned hair and an particular individual.
11 percent of all morphological hair matches are found to be non-matches—meaning microscopic hair comparisons are presumptive in nature—must be confirmed by DNA comparisons .

22. Hair structre Hair tip Hair shaft Hair root Hair cuticle Hair cortex
Hair medulla
毛发结构：毛发是皮肤的一种特殊的附属器，是皮肤毛囊细胞产生的一种富有弹性角质体。
毛尖-----是毛干的游离末端，毛干向毛尖逐渐变细而尖
毛干-----是裸露于皮肤外部的部分，由角化上皮细胞组成，中心向外可以分为：
毛小皮：人----毛小皮花纹通常为细小波浪状。
毛皮质：人----皮质发达，
毛髓质：人---髓质不发达、而且髓质不连续
毛根-----是埋在皮肤内的部分。
毛 球：毛根起始端膨大和球状的部分
毛 囊：包裹毛根的一管状结构，内层为上皮根鞘、外层为纤维组织鞘
毛乳头：毛球和毛囊末端膨大，底面内凹，含毛细血管和神经的结缔组
Hair bulb
Hair root
Hair follicle
Hair papilla

23. Hair growth 1. Anagen Phase(生长初期) 2. Catagen Phase（生长中期）
3. Telogen phase（终期）

24. Hair growth Anagen Phase Catagen Phase 2-4 weeks Telogen phase
2-6 years
2-4 weeks
Telogen phase
2-6 months 24

25. 1. Anagen Phase
Initial growth phase during which hair follicle is actively producing hair
phase may last 2-6 years, root is flame like in appearance.
When pulled this root may contain a follicular tag (rich source of DNA)

26. 2. Catagen Phase
A transition phase—hair grows at a decreasing rate for two to three weeks—elongated appearance as root bulb shrinks and is being pushed out of hair follicle . 26

27. 3. Telogen phase
Hair growth has ended—root takes on a club-like appearance—during two-six month period, the hair will be pushed out of the follicle causing the hair to shed naturally

28. In the anagen phase, hair growth is active and melanin is being produced in the hair bulb at the base of the hair.  This allows maximal heating of the hair follicle and arrest of hair growth.  During the catagen phase, no hair growth or pigment production occurs.  The telogen phase of the hair cycle is marked by the formation of a new hair in the follicle which causes the shedding of the hair.  The hair follicle then recycles back to the anagen phase. 28

29. Morphology: Root
Human hair grows in three developmental stages: anagen, catagen, and telogen phases

30. Hair shape and color

31. 1. Hair shape
Hair shape (round or oval) and texture (curly or straight) is influenced heavily by genes. Nutritional status and intentional alteration (heat curling, "perms") can affect the physical appearance of hair.
毛发的粗细不同，与性别、个体、部位和种族有关。男子一般比女子粗，有人测定过头发约在70～100μm之间。
毛发的长度也不等，毳毛一般在5～6mm以下，超过10mm以上者很少；短毛如睫毛、眉毛、鼻毛等，一般长度也不超过10mm。头发的长度最长，尤其是女子留长发者，有的可长到90～100cm，甚至150cm，据文献记载最长的达3.2m。
通常毛发可分成硬毛与毳毛两类，硬毛粗硬，具有髓质、颜色较深。 31

32. shape band-shaped oval round The African people The European people
asians
round

33. 黄种人——直发；黑种人——螺旋状卷曲
毛发形态与种族、遗传、生长部位有关 33

34. 2. Hair color
Mostly the result of pigments Natural hair color can be black, brown, blond, or red.
Hair color may also be influenced by the optical effects of light reflecting and bouncing off the surfaces of the different hair. 34

35. A variety of the hair colors
A variety of the hair colors. From top left, clockwise: black, brown,blonde, white, red.

36. Color related factors
genetic
aging
stress
disease
artifical factors

38. The distribution of hair
Except for the lip, the palm, the footplate, the finger and the toes.
The body area from which a hair originated can be determined by the sample’s length, shape, size, color, stiffness, curliness, microscopic appearance, pigmentation, and the appearance of the medulla.
Hairs that exhibit similar characteristics from different areas on the body are often referred to as body hairs and include hairs found on the upper legs, lower abdomen, and back.
毛发在人体分布很广，几乎遍及全身，只有掌跖、指趾屈面、指趾末节伸面、唇红区、龟头、包皮内面、小阴唇、大阴唇内侧及阴蒂等处无毛发分布。
全身的毛发数目尚无精确统计，但有人曾测定过头发约有10万根左右。身体各部位毛发的密度不同，随性别、年龄、个体和种族等而异。一般头部最密，头顶部约为300根/cm2，后顶部约为200根/cm2，手背处则很少，只有15～20根/cm2，在前额和颊部毛发密度为躯干和四肢的4～6倍。一般认为毛囊的密度是先天性的，到成人期不能增添新的毛囊数。 38

39. Forensic Analysis of hair
Whether the hair-like evidence in question is hair?
Whether the hair in question originated from an animal or a human?
Can the body area from which a hair originated be determined? Is it possible to determine if a hair was forcibly removed from the body?
Individualize a human hair?
: eg. define nuclear and mitochondrial
DNA—note similarities and differences
毛发检验解决的问题：是毛发还是纤维；是人毛发还是动物毛发；体不同部位的鉴别；毛发的损伤鉴定；个人识别． 39

40. Hair ? How to distinguish difference between hair and fiber ？
Visual examination
Microscopy examination
Burning
1．肉眼观察典型的毛发有毛尖、毛干和毛根的结构特征，与天然纤维、合成纤维区别明显。
2．显微镜观察人毛或动物毛有毛小皮、皮质、髓质三层结构，纤维无此结构，易于区分。
3．燃烧法纤维易燃，燃烧后一般无特殊臭味，人毛或动物毛燃烧后会发出特殊的臭味
Hair ?

41. Human hair? Animal hair?

42. The scale pattern of the cuticle in human hairs is routinely imbricate
The scale pattern of the cuticle in human hairs is routinely imbricate. Animal hairs exhibit more variable scale patterns.
human
显微镜下一般观察到7种毛小皮形态。包括棘状鳞片、齿状鳞片、多面型鳞片、鱼形鳞片、环纹型鳞片、多面型鳞片及不规则花环型鳞片。其中不规则花环型鳞片多见于人和一些哺乳动物。人毛毛小皮印痕呈较细而不规则波浪花形或细锯齿状，动物毛小皮形状多变、小皮缘为粗锯齿状。
Bat Hair
Mink Hair
Hair cuticle 42

43. human

44. dog

45. rabbit

46. human
Cortex&medulla
The shape of the hair shaft is also more variable in animal hairs. 46

47. Five regions of a Single Head Hair
Five regions of a Single Head Hair (Proximal to Distal)

48. Whether a hair was forcibly removed from the body or not?
脱落----毛根完全角化，干燥萎缩，无根鞘附着，根部色素少。染色不颜色反应
拔出----毛囊组织附着、毛球湿润，毛球下端开放呈钩状，染色呈红色。毛发被拉长，滴加水毛发可自然回缩。
钝器损伤----钝器作用部位变宽扁平，皮质纤维分离，部分或完全断裂
锐器损伤----断端平滑整齐、毛干不碎裂、皮质纤维不分裂
高温情况下可引起色泽变化。温度超过150℃毛发因高热缺水分，出现形态结构的改变。190℃发角质膨胀、熔融、出现气泡。200℃以上黑发变成黑褐色，白发则变成黄色、红色并失去光泽。240℃毛发卷缩，随着温度的升高，毛发则发生炭化。烫发对毛小皮有明显的损伤，可见毛皮质出现小裂缝或气泡，皮质纤维高度扭曲并呈一定角度，毛发干燥，易碎易断。

49. 脱落----毛根完全角化，干燥萎缩，无根鞘附着，根部色素少。染色不颜色反应
拔出----毛囊组织附着、毛球湿润，毛球下端开放呈钩状，染色呈红色。毛发被拉长，滴加水毛发可自然回缩。
Human head hair with attached tissue indicating the hair was forcefully removed from the scalp. 49

50. Hair damage
Cut

51. Heat
Hair damage

52. Blunt tool damage

53. Hair damage
Sharp tool damage

54. Scissor-Cut Hair
Hair damage
Razor-Cut Hair

55. Genetic Marker
DNA
Blood type
Protein
Nuclear DNA
mitochondria DNA

56. DNA Analysis hair follicle hair shaft mtDNA Analysis
Nuclear DNA Analysis
毛囊的DNA提取：取带毛囊的毛发数根，用chelex-100法提取DNA。从案件现场获得带毛根的毛发是极为有限的，用chelex-100法提取DNA适用于该类微量物证检材。提取过程中检材不需反复转移，可以避免DNA的丢失，因此该法是提取毛囊中DNA的首选方法。
hair shaft
mtDNA Analysis

57. Nuclear DNA Analysis
STR
SNP

58. mt DNA 母 系 遗 传 拷 贝 多 58

59. Thank you