Crime Scene Investigation quiz Chps 10-12

gush/splash

An irregular pattern created when blood is ejected in volume.

loose contact

The muzzle is in extremely close proximity to the skin, but at the moment of firing, a small gap is created between the two.

mathematical method

gets angle of impact as well as height for projectile

impact pattern

A radiating pattern of small circular or elliptical-shaped stains created when blood is broken up at a source by some force.

zones of possibiity

In seeking to understand the shooting scene, the crime scene technician realizes that all of the associated evidence and artifacts can lead to establishing possible and impossible areas where shooting events occurred.; each zone is labelled: zone 1 is most probable, 2 is awkward, and 3 is impossible given the data

pattern diversity principle

One way of articulating this principle is to say: the variations in combinations of blood volumes and forces acting on those volumes lead to recognizable classes of patterns.

spurt pattern

Stains created when blood is ejected in a stream under pressure or with velocity, most often encountered when an artery or the heart is breached.

cast-off

Stains created when blood is flung from an object that is either in motion or which suddenly stops some motion.

near contact

The muzzle is generally said to be not more than 5 in. from the skin.

close or hard contact

The muzzle is in direct contact with the skin or pressed into the skin.

intermediate range

The muzzle is typically between 5 and 40 in. (a general maximum of 40 in. is usually identified, but the internal ballistics information from the firearms examiner may alter this maximum distance). Intermediate-range gunshot wounds are deduced singularly from the presence of stippling around the wound.

bullet impact angle based on defect shape

There is an empirical relationship between the shape of the bullet defect and the angle of the bullet's impact into the target. This relationship was first observed and validated in terms of blood droplets impacting targets,7 but the relationship is based on the nature of the defect caused when an object with a circular cross section (an object that is either cylindrical or spherical) strikes a target.

indeterminate range

This determination means that no conclusion can be drawn on muzzle distance. This determination is found in situations where there are no markings except for the bullet defect.

crime scene techs

are the group responsible for conducting external ballistics. This area of ballistics considers the path and trajectory of the bullet after leaving the barrel of the weapon to its final impact.

forensic firearms examiners

are the people who deal with internal ballistics. this is the study and examination of the firearm itself, which also includes ejection patterns, gunshot residue deposition, and other related aspects

categories of injury based on mechanism

asphyxia, sharp force trauma, blunt force trauma, and gunshot trauma

directionality and impact angle

considered together, the impact and directional angles for a number of stains associated with an impact event (a point source dispersion of blood) may define the origin of the stains in three dimensions.

bloodstain pattern analysis

considers the location, shape, size, distribution, and other physical characteristics of bloodstains in the scene, and from this derives information regarding the nature of the event that created the pattern.

forensic pathologists

deal with terminal ballistics. This is the consideration of the effect of the bullet on a human target and includes defining the path of the bullet through the victim.

narrative description of body should include

general features and specific features

Ballistics is broken down into three areas of study

internal or interior terminal external or exterior

livor mortis

involves settling of blood in the body due to gravity after blood circulation ends. It may present itself as a light red to dark purple coloration in as little as 30 min following death.

the wake effect

involves small fracture lines in paint arching out and away from the defect

decomp

involves the physical putrefaction of the tissue due to bacteria.

rigor mortis

is an evident stiffening of the muscles of the body. Rigor mortis affects all muscles of the body at the same rate. However, it is typically evident in the smaller muscles (e.g., jaw and face) first and then manifests itself in larger muscle groups such as the extremities.

algor mortis

is the loss of body heat from the corpse. The most common approach to determining body temperature is core temperature reading of the liver.

what happened to a bullet if the defect is not round

it must have hit a primary target and become destabilized

physically altered bloodstain principle

once exposed, blood will react to environmental conditions (e.g., airflow, temperature, humidity, variations of surface) in a predictable manner. This principle is a simple recognition that blood dries, wicks, permeates, and coagulates in and on surfaces in a somewhat predictable fashion.

three underlying principles for bloodstain pattern analyst

pattern diversity principle, principle of stain shape and vector correlation, and physically altered bloodstain principle

types of bullet injuries

penetrating, perforating, tangential, grazing

classifying blood patterns

problematic; there are numerous classification systems currently being utilized. Antagonists use this issue to deride bloodstain pattern analysis as unscientific, but this issue is easily understood and explained.

trajectory analysis documentation

requires the same level of documentation and establishing shots as blood splatter analysis, you need evidence establishing photos, context needs to be made, photos of trajectory rods need to be taken, numbering also needs to be done so each defect is distinguishable in evidence establishment

stain shape and vector correlation principle

significant consideration in the examination of a variety of stains found in crime scenes. It involves two primary subprinciples: directionality and impact angle. The general principle can be articulated as: the shape of certain bloodstains provides indicators as to the direction of deposition as well as to the spatial origin of the blood.

body as crime scene

the corpse is approached in a similar fashion as any crime scene. Thus the technician must assess, observe, document, search, collect, and analyze it.

stippling

the embedding of unburned and partially burned gunpowder residues in the skin

perforating injuries

where the bullet enters and exits

penetrating injuries

where the bullet enters but does not exit

tangential injuries

where the bullet skims the surface producing several shallow wounds

ricochet or deflection

where the bullet strikes a surface and deflects off it at some angle without penetrating the surface completely

grazing injuries

where the projectile leaves only a minor abrasion as it passes adjacent to the body

three types of characteristics on bullet or bullet fragment

• Layering of trace evidence, indicative of sequence of targets struck • Damage to the projectile, indicative of the type of target the bullet struck • Deformation of the projectile, indicative of a deflection along its flight path and the angle of the deflection