Examination of Hairs and Fibre (Chemistry)

Question 1

What percentage of hair/fibres are lost within the first 4 hours from contact transfer?

Answer 1

~ 80%

Question 2

What are the 4 factors affecting rate of loss?

Answer 2

• Type of donor/recipient textiles
• Length of hair/fibre
• Environment conditions
  ex. snow, rain, etc.
• Handling/cleaning

Question 3

What are the 2 methods for collecting hairs/fibres?

Answer 3

• Taping

- Picking up by eye or under a stereomicroscope

Question 4

What is seen as “proper handling of evidence”?

Answer 4

• Case items are segregates into groups with originated from a common source
• A sequence is closed for taping items from different sources so that potential contamination is minimized
• Items from different sources are taped in different h&f taping rooms by qualifies h&f personnel
• A different lab coat is worn for taping items from different sources
• Work area is cleaned before and after taping and mounting
• Examiners clothes are taped for control purposes
• Could take weeks or months to examine fibres and collect DNA

Question 5

What are the 3 stages of Haie=r growth?

Answer 5

Hair growth*
- Anagen Phase:
    > Actively growing phase (80-90%)
    > 2-7 years for human
- Catagen Phase:
    > Transition phase 
    > A few weeks
- Telegen Phase:
    > Resting phase (10%)
    > A few months
    > Will fall out naturally
    > Can have skin tissue attached to is (dandruff)

Question 6

What can you use to identify wool versus animal hair?

Answer 6

The Mandala

Question 7

True or False: Individual Textile and Trace Evidence fibres are weak and are easily transferred?

Answer 7

True!

Question 8

Take a quick 20 second break!

You deserve it!!

Answer 8

Meanwhile, here’s a fun fact:

Saliva has three times the boiling point of water!!!

Question 9

What are the types of damages a fibre can have?

Answer 9

• Cuts: sharp clean edge, but after washing it is no longer obvious if it’s a cut or a tear
• Tear: fibre break at weakest point
• Seam Separation
• Abrasions - gun hole
• Thermal Damage
• Distorted Elastic: in sexual assault