Pathology, Radiology, Hair, Fiber, Fingerprints- Unit 5

Final Exam

Visible Prints

Seen with unaided eye. Blood, ink, paint, oil transfers

Latent Prints

Invisible prints. Dusting powder with a brush to help visualize print

Impression Print

Clay, putty, wax, playdoh impression

How to preserve fingerprint

Prints are photographed to scale. Use tape to carefully lift up and preserve evidence.

Different types of fingerprint patterns

Arch, loop, whorl patterns

Delta

Point of ridge divergence meeting looping ridges (triangle shaped area)

Core

Where a loop pattern reaches its farthest point towards the middle of print and starts to turn back

Different minutiae patterns

Bifurcation, ridge ending, ridge dot, lake, hook, bridge, island

How fingerprint analysis is done and its limitations

Expert compares F.P. found at crime scene with known fingerprint by examining the minutiae patterns.

Limitation- Not always will there be a fill near fingerprint to examine, don’t know if it is relevant to the crime scene (was it there before, during, or after?), examiner bias

FBI fingerprinting database

IAFIS

3 parts to hair

Cuticle- outermost layer of hair shaft

cortex-Lower layer under cuticle

medulla- innermost component of hair

3 stages of Hair Growth

Anagen- Active growth occurs

Catagen- Transitional phase

Telogen- Resting period for follicle

(Exogen- Loss of hair shaft from follicle)

How is hair evidence collected/preserved?

1. Collected with tweezers, tape lifting, or vacuuming

2. Each hair is packaged separately in paper bags sealed and labeled

How hair analysis is done and its limitations

Experts use a stereo microscope to view the surface of hair shaft or a light microscope for viewing the medulla.

Limitations- Can’t specify who’s hair it is, potential bias

Autopsy

Helps pathologists examine internal and external parts of body

Steps of an autopsy

1- External examination (tattoos, scars, birthmarks…)

2- Internal examination (Y incision is made to expose organs from shoulder-breastbones)

3- Viewing internal organs (ribs sawn off to expose internal organs)

4- Removal of organs (Rokitansky method (removing all organs at once))

5- Removal of brains (Incision made in the back of scalp from ear-ear)

6- Examining organs (All organs except stomach and intestines are weighed)

7- Returning organs to body (organs returned to body except for small tissue frags. for microscope examination)

8- Sewing up the body (Incisions stitched up like a baseball)

Questions to be answered in death investigation

Manner, cause, time of death (PMI)

Manner of Death

Classification of death- Homicide, suicide, natural, accidental, undetermined

Homicide- Death caused by another person (murder or manslaughter)

Suicide- Someone kills themselves

Accidental- Arise from violent, unexpected death

Natural- Heart disease, cancer, stroke

Cause of Death

Medical reason for death

Mechanism of Death

Actual biochemical means by which someone dies