Understanding of the Patterns and Shapes Formed when Blood Droplets Impact Upon Various Surfaces – Lab Report Example

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The paper "Understanding of the Patterns and Shapes Formed when Blood Droplets Impact Upon Various Surfaces " is an excellent example of a lab report on biology. Over the past decades, bloodstain pattern analysis of human blood has acquired a greater recognition as a blood spatter patterns are commonly found at crime scenes. Bloodstain pattern interpretation is usually undertaken to recreate the likely actions that may have caused the blood to spatter (Bevel & Gardner, 2008). Bloodstain pattern expert analysts examine details such as location, size, shape, the appearance of stains and patterns, geometry, and location of the bloodstains to come up with opinions of what happened at a crime scene.

Thus, it is important that blood stains are well documented and preserved so that they remain in their original state for later examination. The factors essential to be recorded in a bloodstain pattern analysis in order to have a correct interpretation of a bloodstain pattern include the overall shape of the pattern, the shape of blood spatter, absorbance properties of the substrate, surface characteristics of the substrate, and the texture of the substrate (The Forensic Library, 2017). Bloodstain pattern analysis uses principles of biology, physics, and mathematics to help forensic investigators to interpret bloodstain patterns correctly and answer questions such as: Why did the blood originate?

What caused the bleeding? From what directions was the person wounded? How were the perpetrator and victim positioned at the time of the event? What movements occurred after wounding? How many crime perpetrators were actually present at a crime scene? Is there an agreement between bloodstain evidence and witness statements? Bloodstain pattern analysis also provides information on what could have not possibly happened, assisting the investigator to reconstruct crime events, refute or support witness statements, include or exclude suspected perpetrators of the crime from the investigation, and exonerate perpetrators of a crime.

Interpretation of a bloodstain pattern is subject to the information available and the analyst’ s ability to perform the blood examination process (Albalooshi & Eltabie, 2015). Principles of Bloodstain Pattern Interpretation To understand how the interpretation of bloodstains is performed, one must be able to the basic properties of blood. Analysts use the behavior of blood [biology], capillary action, cohesion, and velocity [physics], distance, geometry, and angle [mathematics] to interpret bloodstain patterns.

Blood is composed of both the liquid parts and the solids part. The liquid part is made of blood plasma and serum, while the solids part is made of white blood cells, red blood cells, proteins, and platelets (James, Kish, & Sutton, 2005). When inside the body, the blood is in the liquid state. Except for people with hemophilic condition, blood does not remain in a liquid state for long after exiting the body but begins to clot in a few minutes to form a dark, shiny gel-like substance that hardens with time.

Blood may exit from the body in different ways depending on how the injury is inflicted. These ways include: dripping, flowing, spurting, spraying, gushing, or oozing [for wounds]. Because drops of blood demonstrate cohesion forces or surface tension, they drop at an angle which may also be affected by the surface of impact (Bevel & Gardner, 2008). Smoother surfaces have little distortion whereas rougher surfaces affect the surface tension causing the drops to break apart.

The location, number, and volume of bloodstains influence the amount of useful information that can be gathered from a scene (Parker, 2014).

References

Albalooshi, Y. M., & Eltabie, M. A. The Importance of Bloodstain Pattern Analysis in the Investigation of Road Traffic Accidents: A Case Report. Arab Journal of Forensic Sciences and Forensic Medicine 2015: 1(2), 224-228.

Bevel, T., & Gardner, R. M. Bloodstain Pattern Analysis with an Introduction to Crime Scene Reconstruction. New York: CRC Press;2008.p.12-13.

Eckert, W. G., & James, S. H. Interpretation of Bloodstain Evidence at Crime Scenes. New York: CRC Press;1998.p.10-80.

Gardner, R. M., & Bevel, T. Practical Crime Scene Analysis and Reconstruction. New York: CRC Press;2009.p.11-16.

Hodge, N., Short, S., & Page, J. (2017). Blood pattern analysis. Retrieved from Forensic Equity: http://www.forensicequity.com/blood-pattern-analysis--l2-42.html

James, S. H. Scientific and Legal Applications of Bloodstain Pattern Interpretation. New York: CRC Press;1998.p. 33-37.

James, S. H., Kish, P. E., & Sutton, T. P. Principles of Bloodstain Pattern Analysis: Theory and Practice. New York: CRC Press;2005.p.1-10.

Kettner, M., Schmidt, A., Windgassen, M., Schmidt, P., Wagner, C., & Ramsthaler, F. Impact height and wall distance in bloodstain pattern analysis—what patterns of round bloodstains can tell us. International Journal of Legal Medicine 2015: 129-133.

Parker, N. L. Crime Scene Bloodstain Pattern Analysis Workbook. United States: Author House;2014.p.107-109.

The Forensic Library. (2017). Bloodstain Pattern Analysis. Retrieved from The Forensic Library: http://aboutforensics.co.uk/bloodstain-pattern-analysis/

White, P. Crime Scene to Court: The Essentials of Forensic Science. London: Royal Society of Chemistry;2004.p.115-138.

Wonder, A. Y. Bloodstain Pattern Evidence: Objective Approaches and Case Applications. United States: Academic Press;2011.p.3-33.

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