Forensic Hair and Fibers

Which two characteristics of a hair help determine if the hair came from a human or animal?

• Medulla pattern and cuticle type

• Color and length

• Thickness and texture

• Curliness and elasticity

When observing a cat hair image under the microscope, it is possible to contrast it to a human hair by observing the —

• DNA

• distribution of pigment

• medullary pattern

• presence of keratin

Tags

NGSS.MS-LS4-4

What class characteristics of hairs are used by lab technicians to either rule out a suspect or determine if further analysis is needed to confirm consistency with crime scene samples?

When examining a fiber using a polarizing microscope, the characteristic that would distinguish a textile fiber from an animal hair is —

• presence of cuticle scales

• a crystalline structure

• melanin in cortex

• a uniform diameter

A young child is kidnapped from her school playground. Shown below is a reference sample of the kidnapped child's hair. The only cars that left the parking lot before the child was discovered to be missing were those of four cafeteria workers. The car of each worker was searched below. Which recovered hair, if any, is consistent with that of the victim and warrants further investigation?

• Worker A

• Worker B

• Worker C

• Worker D

What is the medullary index for a human hair?

• generally less than 1/3

• generally equal to 1/3

• generally more than 1/3

• generally greater than 1/2

The most important structure for the individualization of hair (identity).

• Medulla

• Cuticle

• Cortex

• Follicle

If the hairs were an exact match when compared under a microscope, is that enough to place the suspect in jail? Why or why not?

• Yes, because a microscopic match is conclusive evidence.

• No, does not contain the root, no DNA, so this is class evidence

• Yes, because it proves the suspect was at the crime scene.

• No, because hair evidence is not admissible in court.

Fibers are commonly examined by a microscope that changes typical scattered light wavelengths into wavelengths that vibrate in only one direction, which enhances contrast. This process describes which microscopy analysis?

• Polarizing Microscopy

• Comparison Microscopy

• Oblique Lighting Microscopy

• Transmission Electron Microscopy

A man sustained blunt force trauma to his head. A hammer, which was found in close proximity to the man, was collected for evidentiary purposes. A closer look at the hammer revealed hairs on the end of the hammer. How should the hairs be packaged?

• Sealed in an envelope.

• Sealed in a paper bag.

• Sealed in a plastic bag.

• The hairs should be left alone and packaged with the hammer.