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Blood and Blood Spatter homework page 10-13 summary

Blood Spatter -"when a wound is inflicted and blood leaves the body, a blood- spatter pattern may be created" -"a single stain or drop of blood does not constitute a spatter
 * a lot of bloodstains make a blood-spatter pattern
 * blood spatter can help with a shooting, stabbing or beating case.

History of blood-spatter analysis -Pitoroski wrote the earliest reference to blood-spatter analysis. -today blood-spatter evidence is used to explain events as a violent scene

Blood-spatter analysis -blood-spatter can be used to recreate a crime scene. -it is possible to determine the direction the blood was traveling, the angle of impact and the point of origin of the blood -blood spatter can help determine how someone diet, based on the blood velocity

Blood is a thick mixture of blood cells and plasma when someone is hurt and is bleeding, gravity acts on blood, pulling it downward toward the ground the blood droplet has a tendency to become longer that it is wide as a result of gravity -blood is cohesive- this means that the blood mixture is attracted to similar blood mixtures and tends to stick together and not separates as it falls.

When blood hits the ground it usually will make a round, circular shape. When a drop of blood falls on a flat surface, the blood drop will have a curved surface It will not flatten out because of the cohesiveness of the blood- the mixture in the blood pulls together.
 * if any of the blood does overcome cohesion and separate from the main droplet of blood, it will form small secondary droplets know as satellites.

If blood is dropped onto a smooth surface like a glass or marble, the edge of the blood drop appears smooth and circular.

If the blood lands on a porous surface like wood, or ceiling tile, then the edge of the drop of blood may form small spikes or extensions.
 * Spikes are still attached to the main droplet, and satellites are totally separate.

Six Patterns of Blood: 1. Blood falling directly to the floor at a 90 degree angle will produce circular drops, witch secondary satellites being more produce if the surface hit is textured. This is known as a passive fall. 2. Arterial spurts or gushes typically found on walls or ceilings are caused by the pumping action of the heart 3. Splashes are shaped like exclamation points. The shape are position of the spatter pattern can help locate the position of the victim at the time of the attack. 4. Smears are left by a bleeding victim depositing blood as he or she touches or brushes against a wall or furniture 5.trails of blood can be left by a bleeding victim as he or she moves from one location to another. The droplets could be round or smeared or even appear as spurts 6. Pools of blood form around a victim who is bleeding heavily and remains in one place. If the bleeding victim moves to another location, there may appear to be droplets or smearing connecting the first location with a second.

The size and shape of blood droplets help identify the direction from which the blood originated. - spatter patters can help determine the type of wound. - a fine-mist spatter is produced by a high-velocity impact such as a gunshot wound -a beating with a pipe will produce blood cast off witch a low-velocity pattern - voids in a spatter pattern could help determine the presence of a person or object moved after the attack -spatter pattern= can help determine the point of impact or convergence, a two- dimensional representation of the location of the victim at the time of the injury.

the Point of origin- can be determined by the mathematical relationship between the width and length of the blood droplets.

The shape of an individual drop of blood provides clues to the direction from where teh blood came from. - a circular drop of blood means the drop fell straight down -when a blood drop is elongated, it is possible to determine the direction the blood was traveling when it struck a surface. As moving blood strikes a surface, several forces affect the droplets of blood. These forces are cohesion, adhesion.
 * blood dripping from a wound
 * Adhesion is a force between two unlike surfaces, such as blood and the surface of a wall. Cohesion is a force between two similar substances. Surface tension is as elastic characteristic along the outer edge of a liquid caused by the attraction of like molecules.

When blood hits another surface- it tends to stick to it. The point of impact will make the blood darker or lighter.

Lines of convergence: by drawing straight lines down the long axis of the blood spatter and noting when the lines intersect, this will indicate the lines of convergence. When there are many blood spatters the area where the lines of convergence meet is where the source of blood originated.

SIZE OF DROPLETS: less that one-gunshot wounds 1-4- beating, stabbing 4-6- blunt object impact