Forensics Exam #1 Review

Crime scene sketches must include

Crime scene sketches must include

• Objects in the room

• Location of evidence

• Directional north

• The date, time, location

• Case number

Direct evidence

Refers to any piece of evidence that stands alone to prove an assertion, often in the form of the testimony of witnesses or eyewitness accounts

Circumstantial evidence

Indirect evidence that does not, on its face, prove a fact in issue but gives rise to a logical inference that the fact exists. Circumstantial evidence requires drawing additional reasonable inferences in order to support the claim

Trace evidence

Created when objects make contact, and material is transferred

Examples of direct evidence

• When a person testifies that they saw an accused commit a crime

• When a person heard another person say a certain word or words, or observed a certain act take place

Examples of circumstantial evidence

• Physical evidence (fingerprints, hair, blood)

• Human behavior

• Indirect witness testimony

• Scientific evidence

• A suspect in a crime was seen by a witness fleeing the scene on foot after a convenience store robbery

Is a combination of circumstantial evidence enough to convict someone?

Yes

Which is stronger direct witnesses or circumstantial evidence?

Direct witnesses

Examples of trace evidence

• Fibers

• Hair

• Soil

• Wood

• Gunshot residue

• Pollen

• Paint

• Glass

Are fingerprints different on every single finger and toe?

Yes

What things create the individual characteristics of a fingerprint?

• Ridge patterns

• Minutiae

Do fingerprint stay the same your whole life?

Yes, apart from damages caused by scars or disease

Core

Delta

Ulnar loop

Radial loop

Plain whorl

Central pocket loop whorl

Double loop whorl

Accidental whorl

Plain arch

Tented arch

What are latent fingerprints?

Traces of sweat, oil, or other natural secretions on the skin, and they are not ordinarily visible. Latent fingerprints can be made visible by dusting techniques when the surface is hard and by chemical techniques when the surface is porous

What are plastic fingerprints?

A fingerprint that has been pressed, molded, or shaped into something else, usually a softer material such as dirt, mud, or clay. The plastic prints definition can also be applied to softer surfaces found in the common household such as a bar of soap, wet paint, or wax

What are patent fingerprints?

Also known interchangeably as visible fingerprints, fingerprints that are left behind when an individual has some form of liquid (or powder, in some cases) on their fingers. The most common types of liquids associated with visible fingerprints include blood, ink, grease, and dirt

How are latent fingerprints collected?

• Latent print fluorescence, dusting with fluorescent powders, staining with fluorescent dyes, and treatment with compounds such as fluorescamine can produce satisfactory prints

• Chemicals: cyanoacrylate fuming

How are plastic fingerprints collected?

Usually photographed under oblique lighting that enhances the contrast of the ridges and furrows. These prints may also be preserved with silicone-type casting materials

How are patent fingerprints collected?

Using a fairly straightforward method: photography. These prints are photographed in high resolution with a forensic measurement scale in the image for reference

Bifurcation

Bridge

Eye/enclosure/lake

Ending ridge

Crossover

Dots/islands

Short ridge

Hook

Human vs. small animal hair: color variation

• Human: Generally the same color from one end to another

• Animal: Color can vary from tip to root

Human vs. small animal hair: root shape

• Human: Club shaped

• Animal: Can be spade shaped or frayed

Human vs. small animal hair: end shape

• Human: May have split ends

• Animal: Generally does not have split ends

Imbricate

Spinus

Coronal

Imbricate

Spinus

Coronal

What animals typically have imbricate cuticles?

Humans, some bats, some cats, some rodents

What animals typically have spinus cuticles?

Some cats, seals, mink, rabbits, some rodents

What animals typically have coronal cuticles?

Some bats, some cats, some rodents

Human medullary index is always ____ and animal medullary index is typically ____

Less than .3, greater than .3

What are the 3 parts of hair?

Cuticle, cortex and medulla

What evidence can you gather from hair?

• Race

• When it was dyed

• Medullary index and pattern

• Hair from different areas (type of crime)

• The stage it is in (pulled out)

• Cuticle patterns

• Cortex color, thickness and texture

How can drugs be detected in hair follicles?

Since it is fed blood via blood vessels, hair follicles will retain detectable traces of blood (drugs content) for up to 90 days

What are the 3 hair phases?

Anagen, catagen, telogen