By- Maya Ellerkmann and Abby Boyer Blood By- Maya Ellerkmann and Abby Boyer

Bloodstain Pattern Analysis the examination of the shapes, locations, and distribution of patterns of bloodstains, in order to provide an interpretation of the physical events that gave rise to their origin

The following Information may be obtained from a proper Bloodstain Pattern Analysis 1. Distance from the blood source to the target 2. Direction of travel and impact angles 3. Nature of the force used to cause the bloodshed 4. The object used to cause the bloodshed 5. Sequencing of multiple bloodshed events 6.Interpretation of contact or transfer patterns

When properly documented, bloodstain patterns found at the crime scene, or on a particular person's clothing, can be used to 1. Confirm or refute the position of a victim, witness, suspect, or defendant 2. Determine if there is evidence of a struggle, or if the assault is "one sided" 3. Confirm or refute statements made by principles in the case:       IE: Are stain patterns on a particular person's clothing consistent            with accounts given by the victim, witness, or defendant?

Blood Flight Characteristics Blood will not break up unless it is acted upon by force. The force must be great enough to overcome the surface tension of the blood. Blood forms a spherical shape (perfect circular shape) almost immediately upon separating from the blood source. The spherical shape is caused by the surface tension of the blood. Surface Tension causes the blood drop to pull itself in; both horizontally and vertically. The blood drop will settle into a spherical shape, as a result of the surface tension. The surface tension will maintain the sphere shape of the blood drop until it impacts with the surface.

SPATTER VS TRANSFER The simplest type of blood spatter analysis is determining spatters from transfers. Spatters are created when blood is acted upon by force, and travels through the air before landing on a target surface. Transfers occur when a blood source comes in direct contact with a target surface area.

Transfer - Swipe Pattern

Spatter Pattern

Transfer - Wipe Pattern

TARGET SURFACE TEXTURE Bloodstains can occur on a variety of surfaces. The type of surface that free falling blood strikes affects the appearance of the resulting spatter. or regular circular shape. Blood drops on a rough surface will make an irregular shaped stain with rough or jagged edges.

LOW FORCE (VELOCITY) IMPACT SPATTER/PASSIVE DROPS

MEDIUM FORCE (VELOCITY) IMPACT SPATTER: OR PROJECTED SPATTER

HIGH FORCE (VELOCITY) IMPACT SPATTER

Angle of Impact:   The steeper the impact, the more elliptical or elongated, the blood drop

Direction: The "tail" points to the direction of the blood drop

Citations http://www.crimescene-forensics.com/Blood_Stains.html