CHEM 125 Chapter 1-4 6, 10

Forensic Science is the application fo science to

Criminal Law

What is example of something that would be NOT included in the biology unit?

Fingerprint analysis

Forensic Science is the

Application of Science to Law

Criminalistics

Principles and techniques of physical and natural sciences applied to crime scene analysis; scientist

Scientific method

Form investigative question

Form reasonable (falsifible) hypothesis to answer question

Test Hypothesis through experimentation

Validate hypothesis and make suitable for scientifc evidence.

Phsycial Sceince Unit

Applies chemsitry, physics and geology

Identifyies/ compare physcial evidence

Biology Unit

Applies knowledge of bioloogical sciences identify and perform DNA profiling

—Examples—-

• DNA profiling (dried bloodstains

• Biological fluids

• Hairs

• Fibers

Firearms Unit

Invesitgates bullets, cartridge cases, shotgun shells and ammunition.

Tool mark comparisions also can be made

Document Examination Unit

handwriting analysis and other types of documents such as

• Obliterations

• Erasures

• Burnt Documents

Photography Unit

Applies techniques to record and examine physical evidence

Toxicology Unit

Examines body fluids and complete for presence of drugs and poisons

Latent Fingerpirnt unit

Prcessess and examines evidence for latent fingerprint

Polygraphy unit

Conducts polygraph tests

Voiceprint analysis unit

attemtps to ling recorded voice to a particuar suspect

Crime-Scene recontrstuction unit

Trained personel collected and perserve physcial evidence

Expert witness

person has knowledge relevant to trial that avg person woudnt

Frye v. United States

Case set guidelines for determining admissibility of scientifc evidence in court room

The Concept of “general acceptance” of scientific evidence realtes to the

Frye Standard

Daubert v. Merrel Dow Pharma INC

Case that said the Frye standard is not something that can be fully relied on for the admissibilty if the scientiffic evidnce

Daubert v. Merrel Dow Pharama adovicated for a “gatekeeper” to determine admissibility and reliabilyt of scientific evidnce. Who is the GATEKEEPER

Trial Judge

After providing meidcal assitance for the injured and efffecting an arrest of suspets (if possible) the first officer arriving at crime scene should DO WHAT?

Secure the scene

Three method for crime scene recording

Photography, sketches and notes

Detalied log includes

personal movement in and out of scene and personel names and time of entry and exit

Crime scene notes begin with

• identity of peron who contacted the investigator

• Time of contatct and arrival at crime scene

• Prelimanry case information

• Personnel present on arrival and thse being contacted

Overview Photography

main entry of crime scene

Medium-range photgraph

Closer to entry with marker

Close-up photography

Just object itself

Close up with measuerment scale

Object and a measuerment with it

Sketch of crime scene

Show measuerments of outside

Show posisble exit entryies and movement of scene

Calarify object sin the scen and describe in notes

Charred debris from an arson scene shoulfd be what?

Packaged in airtight metal paint cans

Evidence with individual chartersitics can lead to a determination of common orgin (singlge source). What would NOT yield SUCH results?

Single-layer paints

Physcial evidnece can be used to exonerate or exclude a person from suspuscion if what?

The standard refrence sample (control) from the person doesnt share

The exmaination of a paint chip found on a hit and run victims garment side-by-side with paint removed from vechile suspected of being involved in the incident is an example of what?

Comparison

Where does the value of class phsycial vidence lies in?

Corroborate events with data in a manner nearly without bias.

Who ultimently determines the signifncance of phsycial evidence in a trial?

The jury

The amount of spatter from a blood droplet falling on a than, non-porus surface is WHAT when comapared to a drop of blood falling on a porus softer surface

LESS THAN

The pointed end of a bloodstain always faces

Its direction of travel

At the crime scene, the string method us used to find the WHAT of an imapct spatter pattern?

Area of orgin

If a murder victims blood is ofund in the mzzel of a firearm MEANS WHAT?

It can conclude that the firearm was present during injury to the victim

THe removal of an object or surface that was located between orgin of blood and the target during the blodstaiin leaves behind WHAT?

A VOID

Under which circumstances have two people beend found to have identical fingerprints?

NONE TO DATE hence makes it an individual charecteristic

Fingerprints are formed During WHAT STAGE OF LIFE

Fetal development

Prints that are not readily visbile are called WHAT?

Latent

What type of fingerpinrts are most likely to be found impressed in soft wax?

Plastic

What is the main ingrident in ordnary glass?

Sand

flotation method detmerines what?

Density

When a bullet penetrates a pain of glass, it leavs a crater-shaped hold that is?

Is wider on the exit side

Fracture pattern of glass usually has what kind of lines?

Radial and concentric lines

Druggies fold

Small amoutns of trace evidencepackaged in folded paper

Evidence from arson scene should be packaged how?

airtight metal or glass containers to prevent loss of accelerant vapors.

Standard/reference sample

phsycial evidence orgin is known such as blood, buccal swab or hair from ssupect; can be comapred to crime scene evidence.

Chain of Custody

Peroson who possesed evidence, where and where of possesion

Four exemption ot court orders

• Exsistance of Emergency circumstances

• Prevent immidate destruction or loss of evidnece

• Search of person and protperty within immediate control of person provided made incident to lawful arrest

• Consent of parties involved

Physical Evidence

All objects that establish crime has or hasnt been committed or provide link to victim/crimnal.

Situation unsalavagable

Invesgaotr cant recognize physcial evidence no amount of lab instruments or technical expertis can help the situation

Evidence wieght

decided by jury

Example of Physcial Evidence

• Blood, semne and saliva

• Documents

• Drugs

• Explosives

  Fibers

• Fingerprints

• Firearms and ammunation

• Glass

• hair

• Organs

• protelum product

• Tool/poweder marks

• Serial #

Identification

Determining substance phsycial and chemical identity with near absoulte certainity as exsisting analytical techniques

Process of Identification

1) Adopt test proceudres that give charectistics results for specifc standard materials

2) Permenant record and able to use to prove ideneity of suspect materials

3) Nuber and type of tests needed to identify substance be suffienct to exclude all other susbtances.

Idenifincation commonly used for?

Drugs, blood, semen, wood, hair, gaosline

Comparison

• determines whether suspect specimen and sample (standard/refrence) have common orgin.

• Both STANDARD and SUSPECT specimen are tested the same way

Forensic Comparison Step 1

Combine sleect properties chose from suspect and standard refrence speciment for comaparison

Forensic Comparison Step 2

Examination compelte, forensic scientist must prepare render conclusion with repect orgin.

Role of Probability

Frequency of occurance of an event

Invidual Charecteristics

Evidence that can be associated to a common source with extremely high degree of probability.

Unique to one person or item specific source

Class Charectersitcs

Evidence associated with only a group and not a single soruce

Value of Class Evidence

Abilty to provide corrroboration of events with data as nearly impossible, free of human error and bias.

Signifncance of Phsycial evidence is detmermined by whom?

Courtroom

IAFIS (Integrated automated fingerprint indentification system

National fngerprint and cirmnal hisoitry system

Combined DNA Index System (CODIS)

FED, state, and local crime lab to electornically exchange and comapre DNA profiles

genonolgy Database

DNA profiles

National integrated Ballistics information Netowrk (NIBIN)

Firearm analysts to acuqire digintize and compare marking made by firearm on bullet and cartrdige casings.

PDQ

Data base fo automotive paitns

SICAR

Shoeprint database

Crime-Scene Reconstruction

Liekly sequecne of events by oberservation and evaluation of phsycial evidence, and statments.

Bullet pathway

Victims bullet wound

Direction of travel

Pointed end of bloodstain always faces direction ofr travel

Impact angle

Can be determeined by the mesuring the shape of the drop and how circular it is.

As angle decreases stain

elongates

impact spatter

object strikes liquid blood

Foward Spatter

projected outward and away from source when projectile creates an exit would

Back Spatter (Blow-Back Spatter)

Projected backward from source when prohjectile creates entrance wound

Area of Convergence

2D plane from which drop in an impact pattern orginated

• Can be established by drawing straight lines through long axis of several individual bloodstains, following line of their tails.

Area of Orgin

3D space which blood was projected; shows ppsotion of victim/suspect in space when tain was produced

• String method used to approx. position of area of orgin using angles of impact of indvidual stains in patterns.

GunShot Spatter

Fine foward spatter from exit wound and back spatter from entrance wound; Not through and through only has back spatter

Drawback effect

Some back spatter strikes gunman and enters gun muzzle

Cast off Spatter

Pattern created when blood-covered object flings blood in an arc onto nearby surface.

Projected Patterns

Victim suffers injury to main artery or heart. (oxygenated bllod tend to be brighter red than blood expelled from imapact wound)

Expirated Patterns

Blood from mouth or nose

Void patterns

Gap where object was first blocking depostion of blood spatter onto target surface or object and spatter depostited onto object or person.

Contact/Transfer Pattern

Created when obejct with blood touches one that deos not have blood on it

Flow Patterns

Made by drops or large amounts of blood flowing by the pull of gravity

Pools

Blood collects at a level and undisturbed place

Drip trail patterns

series of drops that are sperate from toehr patterns formed by blood dripping off an object or injury.

What are Fingerprints?

Reproduction of friction skin ridges found on palm sife of fingers and thumbs

Fingerprints: Principle One

Fingerprints is indivudal to one person and one person only

• Common fingerprint ridge chateristics

  • Bifurcations

  • ridge endings

  • ridge dots

  • enclosures

  • 150 minutates (ridge chateristics)on avg. finger

Fingerprints: Princple One Judicial

Expert must demonstrate point-by-point comaprison in order to prove identity of an individual.

Fingerprints: Principle Two

Fingerprints dont change throughout an indivudals lifetime

Have sweat glands that deposit onto skin

Dermal papillae

layer of cells responsible for forming pattern of the ridges on surface skin.

Epidermis

Dermi

outer layer skin

Inner layer of Skin