Chp. 10,11, and 12 of Crime Scene Two

Area of Origin

the 3D location from which spatter originated

Swipe Pattern

transfer of blood from a blood bearing surface to another surface, characteristics indicate motion.

Vehicle Identification Number (VIN)

17 numbers, 1st- where built 2nd ad 3rd - vehicle manufacturer 4th through 9th- vehicle brand, engine size and type 10th- vehicle year 11th-plant 12th-17th- serial number

Cessation Cast-off Pattern

A bloodstain pattern due to its rapid deceleration.

impact pattern

A bloodstain pattern resulting from an object striking liquid blood.

Forward Spatter Pattern

A bloodstain pattern resulting from blood drops that traveled in the same direction as the impact force.

Expiration Pattern

A bloodstain pattern resulting from blood forced by airflow out of the nose, mouth, or a wound.

Spatter Stain

A bloodstain resulting from a blood drop dispersed through the air due to an external force applied to a source of liquid blood.

Saturation Stain

A bloodstain resulting from the accumulation of liquid blood in an absorbent material.

Bloodstain pattern

A grouping or distribution of bloodstains that indicates through regular or repetitive form, order, or arrangement the manner in which the pattern was deposited.

terminus ante quem

Action preceding another action

Directionality of blood stains

Always towards scallops and satellite stains.

Perimeter Stain

An altered stain that consists of the peripheral characteristics of the original stain. example stain dries and flakes.

Types of contact with a weapon and skin

Close contact/ hard contact: muzzle directly in contact with skin Loose contact: muzzle is in extremely close proximity Near contact: no more than 5 inches from the skin. Intermediate range: between 5-40 inches from skin determined by internal ballistics info. Stippling often occurs Indeterminate range: No conclusion can be made about the distance a weapon is from the skin. i.e. no marks except the bullet defect.

Cartridge

Complete unit of unfired ammunition; casing, bullet, primer, and propellant

Drip Stain

Falling drop due to gravity

Terminus peri quem

Occurring at the same time

External Ballistics terms

Penetrating defect; projectile enters but doesn't exit a surface. Perforating defect: projectile enters and exits a surface. Ricochet or deflection; bullet strikes surface and deflects off it without penetrating the surface completely. Tangential defects; Bullet skims the surface creating a series of defects.

Bullet injuries

Penetrating injuries; bullet enters but doesn't exit Perforating injuries; bullet enter and exits tangential injuries; bullet skims the skins surface leaving sharp shallow wounds. Grazing injuries; minor abrasions due to projectile. Like a skid mark.

Presumptive tests for blood

Phenolphthalein (ethonal and hydrogen peroxide) Pink color and leuco-malachite green

PAB

Physically altered bloodstain principle blood reacts to environmental conditions. Methodology: -familiar with whole scene -ID discrete patterns among various surfaces -Classify patterns -Directionality and motion -Angle of Impact, points of convergence, and areas of origin -Variable source events to explain -Validate with peers

What are you looking for in a chemical test of Bullet defects

Presence of Lead and copper. Lead is deposited of the surface of a defect from the friction of the bullet with a surface, and ionized lead from the gaseous discharge. Similarly Primer residues can occur the same way.

Cartridge case

Subunit of the cartridge which holds the primer and propellant

Crime Scene Reconstruction Principles

Superposition; layers in a crime scene Continuity; association made between artifact and dissociated strata. Chronology; every action has another that proceeds or follows it. Relationship; Locards principle

Projected pattern

pattern due to ejection of a volume of blood under pressure.

Bubble ring

results when a ring outlines the bloodstain due to air in the blood.

Pattern Diversity Principle

The variations in combinations of blood volumes and forces acting on those volumes lead to recognizable classes of patterns.

Were can you find a VIN on a vehicle

Under the hood at the front of the engine, Drivers side interior dash, between front crd and windshield washer unit, trunk under spare tire, rear wheel well, driver door jam

How to determine bullet entrance angle

W/L = N (sin-1 of N= angle)

Zones of possibilities

Zone 1; most probable trajectory Zone 2: possible but awkward Zone 3; Impossible

wipe pattern

a bloodstain pattern created when an object moves through an existing stain, removing it or changing its appearance

Basic Methods of Injury

Asphyxia: Lack of oxygen or inability to expel CO2 Sharp Force Trauma: Wider rather than deeper Blunt Force Trauma: Deeper rather than wider Gunshot trauma: Projectile

Theory of bloodstain pattern analysis

Blood as a fluid responds to variations of internal and external forces in a predictable fashion.

Backspatter Pattern

Blood droplets travel in direction opposite of the path of external force applied. (entrance wound created by projectiles)

Flow pattern

Bloodstain pattern due to movement of a volume of blood on a surface because of gravity of movement of target.

Cast off pattern

Bloodstain pattern due to objects motion.

Splash Pattern

Bloodstain pattern which results from a volume of liquid blood falling or spilling.

Conning effect

Entry side has an abrupt edge while exit side will have coning a sloped angle to it.

Projectile/bullet

Expelled from the firearm due to the pressure within a weapon created by the burning propellant. Also called a "shot" in the case of not solid metal bullets.

Three terms associated with the reconstruction process

Incident; overall situation being investigated. Events; macro components, large portions. event segments; micro components, breaking down the events into smaller actions

Three areas of ballistics study

Internal or interior ballistics: Forensic firearm examiners, deal with the weapon, ejection patterns, GRD. Class/ individual characteristics, associating items to one another. Terminal ballistics: Forensic pathologist, path of the bullet through or in humans. External or exterior ballistics: Crime scene tech path, trajectory after leaving the barrel of the weapon.

Enhancing blood

Luminal, amino black, LCV leuco-crystal violet, and fluorescien.

Ejection port

associated with automatic and semiautomatic weapons. where the expended casing is ejected from the chamber.

Concerns when using a trajectory kit

distance between weapon and impact ensuring bullet wasn't tumbling objectively

Terminus post quem

following another action

Blood clot

gelatinous mass formed by a mechanism involving red blood cells, fibrinogen, platelets, and other clotting factors.

Wake effect

lines present in the paint due to projectile moving through the surface.

Serum Stain

liquid portion of blood (serum) separates during coagulation.

Drip Pattern

liquid that drips into another liquid at least one of which is blood.