forensics 25 master set

the accurate chemical name for alcohol found in alcoholic beverages

ethanol

alcohol is produced though the process of

diffusion

the reactants and products involved in the creation of champagne

white grapes + yeast → alcohol + carbon dioxide

which type of alcoholic beverage has the highest concentration of alcohol by volume

distilled spirits

which area of the brain is the first ti be affected noticeably by alcohol that is absorbed into the body

cerebrum

people are considered to be legally impaired in canada if they

have more than 80mg of alcohol per 100mL of blood

the blood alcohol concentration of a person increases when

twenty minutes after drinking alcohol

which country has a higher bac legal limit than canada

swaziland

the countries in which alcohol consumption is not permitted due to religious reasons is

the arab states

cerebrum

causes difficulty hearing and seeing clearly, you don’t exhibit good judgment

cerebellum

makes someone unable to touch their nose w/ closed eyes, and can also cause frequent stumbling and falling

hypothalamus

causes frequent urination where the urine contains a high concentration of water

medulla oblongata

causes a decrease in blood pressure and breathing rate that can lead to unconsciousness

two symptoms of alcohol consumption that may impair one’s ability to drive

1. poor judgment of situations

   • may cause them to turn across traffic or lane change w/o enough time to safely do same, putting themselves and those around in danger

2. jerky or uncoordinated movements

   • may cause the driver to veer into oncoming traffic or into the ditch

when alcohol is absorbed into the blood and is being transporting through the blood what does it not do?

change chemically in any way

how does the concentration of alcohol in the blood compare w/ the concentration of alcohol in the alveoli?

the alcohol concentration is 2100x greater in the alveoli

individualized physical evidence

is unique and can be directly linked to a specific person and/or source

• ex) fingerprints, dna, bullets, bullet casings, dental

  impressions

identified physical evidence

shares a common source; it can be grouped into a class of items having similar properties

• ex) clothing, shoe prints, blood type

why is physical evidence important?

it can confirm the identity of the suspected individual

which type of physical evidence is more important and why?

individualized evidence since it can be linked directly to a specific individual

visible fingerprints

are easily seen by the human eye

• may be left on an object at a crime scene because of blood, perspiration, dirt, or oils on a suspect’s hands

latent fingerprint

are hidden or concealed in some way so they aren’t visible to the naked eye that need to be enhanced in some way to be seen

• usually composed of perspiration and/or body oils

physical fingerprints

leave a distinct impression is left upon soft materials like wax, food items, or the caulking around windows and doors

radial loop (left hand)

ulnar loop (left hand)

ulnar loop (right hand)

radial loop (right hand)

loop fingerprints

• approx 60% of people have this pattern

• lines rise, curve, and return

• sub-classifications are ulnar loop, radial loop, and double-twinned loop

how to distinguish between a right and left fingerprint loop pattern

1. you have two bones in your lower arm: the ulna bone, which is lined up w/ the pinky finger, and your radial bone, which is lined up w/ your thumb

2. the bone that the begins and ends at determines the type of loop

   • known as a road test

3. you must know if the print came from the right or left hand

double-twinned loop

whorl fingerprints

• approx 34% of people have this pattern

• lines form concentric (having a common centre) circles

• sub-classifications are plain whorl, central pocket whorl, and accidental whorl

simple plain whorl

central pocket whorl

accidental whorl

arch fingerprint

• approx 6% of people have this pattern

• lines cross smoothly or upthrust at the centre

• sub-classification are plain simple arch and tented arch

plain simple arch

tented arch

how is a fingerprint impression made?

oils and sweat mix → settle on the finger ridges → finger pad comes into contact w/ an object → the mixture leaves a residue or fingerprint impression

how to enhance a latent fingerprint

1. lifting powder application

2. iodine fumigation

3. cyanoacrylate fumigation

lifting powder application

• works best on smooth, solid surfaces like glasses, door handles, steering wheels, credit cards, car doors, knife blades, and some knife or gun handles

• the powder is usually made of metals like aluminum, tin, iron, or carbon or a combo of homogeneous metals

• used a piece of wide, clear, smooth tape

• the brush has very soft bristles made of bird feathers, squirrel or camel hair, or fiberglass

  • could also have a magnet at the end to attract metal'-based lifting powders not sticking to the surface when applied

iodine fumigation

• human sweat is a mixture of sodium chloride (NaCl)

• fixing solution is used

• iodine crystals give off vapors (sublimation) that adsorb physically to the oily substances of a fingerprint

• turns the fingerprint dark blue after a reaction

• is permanent

cyanoacrylate fumigation

• in a sealed chamber, heat and moisture are introduced and the ‘super glue’ will turn from a liquid to a gas

• works best on dark surfaces w/ smooth or slightly textured surfaces

• needs to be photographed

• turns the impression white

advantages of each latent enhancement method`

1. lifting powder application: useful to identify on hard surfaces

2. iodine fumigation: extremely easy to see

3. cyanoacrylate fumigation: is permanent via photograph

disadvantages of each latent fingerprint enhancement method

1. lifting powder application: inhaling the powder is harmful to the lung tissue

2. iodine fumigation: developed impressions aren’t permanent

3. cyanoacrylate fumigation: leaves a white residue on surrounding surfaces that came into contact w/ the fumes

what latent fingerprint enhancement technique was used on cheri jo bates’s car (zodiac killer case)?

lifting powder

trace evidence

• a general term for evidence that cannot be seen clearly by the human eye

• is significant and should not be ignored

  • common examples are human hair, animal hair, carpet fibers, clothing fibers, glass fragments, and paint fragments.

trace evidence diagram

trace evidence collection procedure

1. securing the Crime Scene and Questioning:

   • police restrict access to the crime scene

   • victims, witnesses, and suspects are questioned

   • no one is allowed in or out until spoken to by the police

   • prevents disturbance of potential evidence

2. observations of the Crime Scene:

   • forensic investigators take photos and videos

   • crime scene details are documented

   • evidence is photographed, and observations are noted

   • trace evidence is lifted using specialized tools

3. collection of Trace Evidence:

   • investigators wear protective suits

   • trace evidence is collected gently to avoid contamination

   • each piece is labeled with relevant details

   • double packaging ensures evidence preservation

   • tools include vacuums, forceps, cotton swabs, and various containers

   • evidence is stored in lockers, with larger ones for homicide cases.

examples of inorganic or synthetic trace evidence

• carpet fiber: household and automobile

• paint

• dust

• soil: silicates, minerals, carbonates, oxides

• glass

• fabrics: nylon, lycra, rayon, polyester, acryluc

• plastics

examples of organic or natural trace evidence

• fabric: cotton, sisal, cashmere, leather, hemp, linen, leather, jute, mohair, wool, silk

• human hair: body, pubic, scalp, eyelash

• carpet fiber: wool, sisal, hemp

• animal hair

• sweat

• blood

• feces

• soil: bacteria, humus, manure, decayed plant/animal matter

• semen

• skin

• saliva

types of human hair

1. head hair:

   • longest body hair; may determine gender

   • sun-bleached or color-treated hair show little variation in the medulla

   • roots may be darker

   • often has cut or split tips

2. body hair:

   • short (less than 1 cm), fine, and thin

   • typically arc-shaped and lighter in color

   • humans shed these hairs less frequently

3. eyebrow or eyelash hair:

   • short (less than 1 cm) and tapered

   • usually darker than head and body hair.

4. pubic hair:

   • dark (brown or black), very curly, stiff

   • thicker and longer (1-2 cm) than body and eyebrow/eyelash hair

various strands of color-treated hair

gross anatomy of a hair

parts of a hair

1. hair root: only part of the hair that requires nutrients and oxygen from a follicle

2. hair tip:

3. hair shaft:

rounded (club) root

a root of human hair that fell out naturally

follicle-attached root

a root of hair that was forcibly removed possibly during a violent struggle where the follicle is still attached to the root (the follicle looks like transparent skin)

dark band root

likely indicates the hair was shed after the person has died :(

frayed root

likely came from a cat

spade-shaped root

likely came from a dog

wineglass-shaped root

likely came from a deer

the hair tip

• can be distinguished from the root since it will never have skin directly attached to it

  • slightly rounded tip: indicates the individual has not cut their hair in a long period of time (likely more the four weeks since last cut)

  • linear or straight tip: indicates individual has recently cut their hair

  • blackened or frayed tip: indicates the individual has come into contact w/ flames or high heat

blackened or frayed tip photograph

the hair shaft

• is found in the region between the root and tip

• three parts of it are called the cuticle (outermost layer), cortex, and medulla (middle region)

imbricate cuticle

scale pattern found in all human hairs and some animals

coronal cuticle

scale pattern found in the hair of bats and small rodents like mice, rats, and vole

spinous cuticle

scale pattern found in the hair of minks, seals, and cats

unisereal medulla

found in hair from a cat or rabbit

lattice medulla

found only in hair from a deer, elk, or goat

multisereal medulla

found in hair from a rabbit or chinchilla

vacuolated medulla

found in hair from a dog, red fox, or cattle

fragmented amorphous medulla

found in human hair of people of hair colors that usually isn’t black

continuous amorphous medulla

found in human hair that is black in color and commonly are of asian decent

what fiber evidence can help prove

1. occurrence of physical contact:

   • discovery of a single transferred fiber increases likelihood of physical contact

   • many fibers found on clothing from suspect, victim, or crime scene strongly suggest contact

   • each fiber is treated as independent evidence

   • multiple pieces of evidence refute the argument of no contact between suspect and victim or crime scene

2. type of contact:

   • violent physical contact over time often leads to the exchange of numerous fibers among suspect, victim, and crime scene

direct (primary) fiber transer

occurs when a fiber is directly exchanged between fabrics

• ex) a suspect's hair on the victim's clothing

indirect (secondary)

happens when a fiber on the suspect is placed on the victim or vice versa

• ex) a carpet fiber from a suspect's home is transferred to the suspect's clothing and then to the victim

natural fibers from plants

1. cotton fibers:

   • helps in crime investigations because of its variations

   • vary in length with some being short while others are long

   • naturally twist in different ways w/ some being tight and others being loose

2. flax fibers:

   • since cotton fibers like white cotton and denim are so common, less common natural plant fibers are more help

     • ex) flax (linen), sisal, jute, and hemp

natural fibers from animals

• most common type is from the wool of sheep

  • coarser or thicker than cotton

• can also be more uncommon wool made from camels, alpacas, cashmere, and mohair

• fine wool fibers are used for clothing while coarser wool is used in carpet

man-made fibres

• are created by machines from natural or synthetic chemicals\

• more than 50% of all fibers are this

• polyester and nylon are the most common w/ acrylic and rayon being the next most common synthetics

• many of those fibers have unique manufacturing-specific textures and shapes

• only only produced for a limited time

what does it mean when red blood cells are anucleated?

is an evolutionary trait that allows oxygen to be carried throughout the body only in human

what is the rarest blood type?

blood type ab

identifying one type of blood enzyme or protein in blood evidence is helpful since?

it helps narrow down the list of suspects

phenolphthalein

• reacts w/ hydroxide ions

• is a colorless acid-base indicator

• turns pink in a basic solution

• the hemoglobin in blood makes the blood basic

• results are immediate

• can detect blood concentration w/ a ratio of 1: 5 million

• gives a positive result for any type of blood

luminol

• is used when investigators suspect the blood evidence has been cleaned up

• is attracted to the iron pigment of red blood cells

• produces a greenish-blue light when it comes into contact

• sensitive w/ the ability to detect blood w/ a ratio of 1: 5 million parts

free-falling blood droplets onto glass

free-falling blood droplet onto cement/concrete

partially dried bloodstain smeared from activity

medium-velocity impact blood spatter from something such as being beaten by a blunt object

high-velocity impact blood spatter from something such as a gunshot wound

why might an investigator spray a crime scene w/ hydrochloric acid before using luminol?

to speed up the decomposition of the red blood cells

fast blue b test

• reacts w/ acid phosphate in the the proteins of the prostate gland’s secretion

  • turns from blue to a deep purple when it comes into contact

• indicates the presence of semen

polygraph test

monitors perspiration, heart rate, blood pressure, and breathing rate

control question technique (cqt)

• aren’t directly related to the criminal case

• used in the pre-test interview

• important to convince the subject that they just as the relevant questions

• used for comparision purposes

relevant/irrelevant technique (i/r)

• is a mixture of questions relevant to the crime and irrelevant questions

  • ex) do you own a handgun? (relevant)

  • are you forty years old? (irrelevant)

• an innocent person will have a similar physiological response to both questions, but a guilty person will react more strongly to the questions relevant to the crime

subject was truthful

suspect was deceptive (lying or misleading)

letters of a forged document are usually?

larger than normal

for a dna match to be declared, how many unique sections of dna must be found?

five