fs fall final review

FS Fall Final Review

Ch 1 and 2observations and CSI

• What factors affect our observations?

• How does the brain process information?

• How could you become a better eyewitness?

Forensic investigators recognize, document, collect, and organize evidence left at the scene of a crime. Factors that affect observational skills such as emotion, perception and recall,time of day, level of interest, number of people…

How does your brain work?

Your brain…

• Filters (what is important, what you notice, your level of interest, who you are with, where you are….)

• Fills in gaps (you may think you saw it…)

• Applies previous knowledge (you sort out issues based on what you know)

Direct vs Indirect

Physical Evidence

Trace

Who does what?

• Who secures the scene and separates witnesses?

• Who takes measurements and notes location of evidence

• Who interviews the witnesses

First Find, then

Why secure the scene?

Identify the regions of hair

What part of the hair is shown?

DNA?

Human or NON-human Cuticle?

Consistent? Dissimilar?Inconclusive?

Is Hair CLASS or INDIVIDUAL evidence?

Medulla

Locard

• Every contact leaves a trace

• Duration

• Intensity

• Materials used

Control?

Fingerprint MinutiaeFingerprint Minutiae

Fingerprints

• Alphonse BertillionAlphonse Bertillion– Anthropometry-use of body Anthropometry-use of body

measurements for identificationmeasurements for identification– Francis Galton-suggested 3 categories-Francis Galton-suggested 3 categories-

Arches, loops and whorlsArches, loops and whorls

• 1999 – 1999 – US v. Byron C. Mitchell-case US v. Byron C. Mitchell-case that provided 3 principles of fprintthat provided 3 principles of fprint

• 1. unique1. unique• 2. unchanging2. unchanging• 3. can be used to ID individuals3. can be used to ID individuals

Kinds of Crime Scene Kinds of Crime Scene PrintsPrints•Patent /Visible prints – Patent /Visible prints –

– made by fingers touching a made by fingers touching a surface after ridges have surface after ridges have been in contact with a colored been in contact with a colored materials (blood, paint, etc.)materials (blood, paint, etc.)

•Plastic Prints – Plastic Prints – – ridge impressions left on a ridge impressions left on a

soft material (putty, wax, soft material (putty, wax, soap or dust)soap or dust)

• Latent/invisible prints – Latent/invisible prints – – caused by the transfer of caused by the transfer of

perspiration/oils on finger perspiration/oils on finger ridges to the surface of an ridges to the surface of an objectobject

Identify each fingerprint pattern.

Right Hand

Left Hand

Left Hand

Right Hand

Right Hand

How can we use these?

What Can be learned from tire impressions?

• What type of impression is shown?

What can you learn from studying the gait (walking pattern)

Why is Chain of Custody so important?