forensic biology

Visible prints

• is a fingerprint that you can see with the naked eye because it was made when a person touched a surface after getting something on their fingers

• like blood, ink, paint, grease, or dirt.

Latent prints

invisible fingerprints left behind by the natural oils, sweat, and other secretions on your skin when you touch a surface. 

• can be found through pingerprint powder and other techniques like superglue fuming.

Antigen

is a substance or molecule that when introduced into the body it triggers the production of an antibody by the immune system. which would kill or neutralize it

Agglutination

clumping of particles—usually red blood cells—that happens when antibodies react with specific antigens on the cell surface.

Secretor

a person whose blood type antigens are also found in their other body fluids—such as saliva, sweat, semen, and tears.

• 80% of people are secretors

Hematocrit

the percentage of red blood cells in the blood

Antibody

a protein that destroys or inactivates a specific protein antigen

• they are found in the blood stream

Immunoassay

a laboratory test that uses the body’s immune system reactions to detect or measure specific substances—like drugs, hormones, or proteins—in a sample (such as blood or urine).

Buffy coat

A layer that contains most of the white blood cells 

• used to extract DNA

• Buffy because its buff and is the colored of naked skin

Blood platelets

small, disc-shaped cell fragments in your blood that help with clotting—stopping bleeding when you get a cut or injury.

• When a blood vessel is damaged, platelets rush to the site.

• They stick together (clump) and form a temporary plug.

Blood Plasma

the liquid part of your blood—it’s what carries all the blood cells and other substances throughout your body

• Clear, straw-colored fluid 

Luminol

a chemical used in forensic science to detect trace amounts of blood, even if it has been cleaned or is invisible to the naked eye.

• It exhibits a blue glow where blood has been

Catagenic

The transition stage where the root is pushed out of the follicle 

• 14-21 days 

• hair keeps growing but the bulb shrinks

Telogenic

hair naturally becomes loose and falls out 

• 100 days

Cuticle

tough, outer layer of hair made of overlapping scales. It helps forensic scientists identify species, compare hair samples, and protect possible DNA evidence.

scales 

differ between species of animals and are names based on their appearance

three types:

• coronal

• spinous

• imbricate

Coronal

or crown-like. Rare in humans typically in rodents.

Spinous

or petal- like. never found in humans mostly in seals, cats and minks.

Imbricate

found in human and are flattened.

cortex

the middle layer of the hair shaft, located between the cuticle and the medulla. It makes up the majority of the hair’s mass and gives the hair its strength, color, and texture.

Melanin

pigment that granulates hair its color

cortical fusi

are air spaces, usually found near the root but may be found throught the hair shaft

Minuate

the tiny, unique ridge details or features found in a fingerprint pattern.
- no two people have exactly the same combination of minutiae.

Lacerations

a tear or split in the skin or tissue caused by a blunt force (not a sharp object).

Incised wounds

s a clean, straight cut in the skin or tissue made by a sharp object — like a knife, razor, or glass.

slash wounds: tend to look like bullet wounds that only graze the surface

punctures: caused by a pointy instrument 

stab wounds: cutting with a balde. its length is greater than its depth

Abraisions

the top layer of skin (epidermis) is scraped off or worn away due to friction or rubbing against a rough surface.
- It’s commonly known as a scrape or graze.

Contusion 

A bruise due to rupture of small blood vessels. A bruise goes through color changes

Fracture

a complete break in the bone

• displacement

• simple fracture

• compound fractutre

Infraction

incomplete break

• hinge fractures

• green stick

Compound Fracture

a broken bone pierces through the skin and becomes exposed to the outside environment.

Comminuted fractures

a break or splinter of a bone into three or more fragments.
It usually happens when a bone is hit by a strong, crushing force

• the bone is shattered into multiple pieces

• Common in high-impact injuries, such as car accidents, gunshot wounds, or severe falls.

Callus

the new bone tissue that forms around the fracture as the bone begins to heal

Describe the three different fingerprint principles.

1) Individuality: No two fingerprints are the same, not even identical twins.

2) Permanence: Fingerprints do not change through a persons lifetime

3) Pattern: All fingerprints are devided into three classes through patterns.

What are the three different type of fingerprints?

1) Loops: (most common) have one delta

2) Whorl: has 2 deltas plain whorl and double whorl

3) Arch: has no delta, plain arch and tented arch.

describe how hair can be used as evidence? what are the three different scales?

Resist chemical decomposition, identify crime victims and criminal suspects, and restrain the same structure over a long period of time.

1) coronal 

2) spinous

3) Imbricate

what are the 6 different body fluids?

1) semen 

2) saliva

3) blood 

4) unrine

5) feces

6) prepiration (release of sweat)

what are the three different blood patterns?

1) Passive bloodstains: Formed by gravity alone—no force other than gravity

• Drops, pools, or drips of blood

• Blood trails from a bleeding person

• Blood flow patterns from wounds

2) Projected bloodstains: Formed when a wet, bloody surface touches another surface

• Bloody handprints or shoeprints

• Wipe or swipe marks (from dragging or cleaning blood)

3) Transfer bloodstains: Formed when a force greater than gravity is applied to blood.

• Low-velocity: larger drops from blunt force (like beating)

• Medium-velocity: small drops from stabbings

• High-velocity: fine mist from gunshots or explosions

what can the study and analysis of blood tell you about a crime?

• distance between the target surface and the origin of the blood.

• movement and direction of a person or object

• number of blows

• the position of a victim

• tools used

• type of impact

• movement of the victim

what are the three different test used for body fluid?

1) Presumptive test: Quick screening tests that indicate if a substance might be a certain body fluid.

• Kastle-Meyer test (for blood – turns pink)

• Luminol (for blood – glows blue in dark)

2) Confirmatory test: Lab tests that confirm what body fluid is actually present.

• Takayama or Teichmann test (confirms blood)

3) Screening: on-site, used to identify the presence of blood on the scene.

serology

the identification and analysis of body fluids

different categories of trauma?

1) Blunt force trauma= caused by impact with a dull or non sharp object

• baseball bat, car accident, fall, fist

2) Sharp Force Trauma: caused by objects with sharp edges that cut or pierce the body

• Knife, axe, glass, razor

3) Projectile trauma= caused by bullets or fireams

4) Burning

5) Dismemberation