Bloodstain Pattern Analysis: Archaeology And Forensics

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Allison Makarewicz Archaeology and Forensics Monday/ Wednesday 1:30 – 2:45 Paper 1 Bloodstain Pattern Analysis (BPA) Bloodstain Pattern Analysis (BPA) is an extremely important method when going over crime scenes. Bloodstain pattern analysis is a tried and tested method of mathematically calculating the location of the source of the spattered blood patterns in a three-dimensional space (International Association of Bloodstain Pattern Analysis 3). Analysts look at bloodstain patterns in order to help police investigators develop a hypothesis about what had occurred and what events were impossible in the situation. Analysts examine the size, the shape, the distribution, and the location of these bloodstains (National Forensic Science Technology…show more content…
Three categories of bloodstains are passive stains, transfer stains, and impact stains. Passive stains are classified as clots, drops (drips), flows, and pools (Bevel and Gardner 93). These are the result of gravitational activity (National Forensic Science Technology Center 3). A clot is a mass of congealed blood and other contaminants created through the body’s natural clotting mechanism (Bevel and Gardner 99). Drops, also called drips, occur when blood drips into standing blood on a vertical or horizontal surface (Bevel and Gardner 107). Transfer stains are classified as wipes, swipes, pattern transfers, and other contact stains (Bevel and Gardner 93). These stains occur when objects come into contact with existing bloodstains (National Forensic Science Technology Center 3). A wipe stain is created when an object moves through a pre-existing bloodstain (Houck and Siegel 245). A swipe stain is the transfer of blood onto a target by moving a object that is already bloodstained (Houck and Siegel 245). A pattern transfer stain is created when a wet bloody object comes into contact with another surface (Bevel and Gardner 119). Impact stains are classified as spatter, splashes, cast-off stains, and arterial spurts or gushes (Bevel and Gardner 93). Forward spatter is when blood droplets are projected away from the object that is creating the impact (Houck and Siegel 246). Back spatter is when blood droplets are projected toward the…show more content…
The main weakness is that it cannot recreate the entire scenario of what occurred because there are unknown variables that cannot be determined using science (National Forensic Science Technology Center 14). One cannot tell the age of the perpetrator. One cannot tell whether an attack was planned. One cannot tell whether the perpetrator was influenced by drugs or alcohol. Another weakness is that there is no standard to test the conclusions of what happened (Bevel and Gardner 26). In conclusion, bloodstain pattern analysis is a good forensics method to use at crime scenes where there is blood. The many different types of bloodstains explain the different scenarios that could have occurred. While bloodstain pattern analysis helps discovered what may or may not have happened, it also has it’s weak points. It cannot tell you anything about the suspect other than where they may have been at the crime

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