Good Bloodstain Pattern Analysis Essay Example

Question 1

When analyzing the blood droplet or bloodstain, the presence of scallops, spatter, tails or spine usually assist the analyst to identify the path that the droplet was travelling in at impact. Unless the impact of the droplet was at 90o, the axis that is associated with the travel direction of the droplet tends to be longer due to droplets skimming action on the target. For example, at an impact of 90o, smaller scallops tend to appear around the stain’s entire periphery. When the impact is 70o, larger scallops tend to be more concentrated on one side of this stain. These scallops tend to be opposite the origin of the droplet, and they point in the direction that droplet was travelling. However, it is perhaps crucial to note that directionality may be hard to establish in circular stains when compared with elliptical stains simply because the concentration of spines in the droplet is not along a single droplet (Bevel, & Gardner, 2008).
Another example is at 50o impact. Here, the scallops have spawned tadpole’s tails. The tails align with the stain’s long axis and virtually point towards the direction of droplet’s travel. However, directionality tends to be less specific when there is only a single tail although an analyst can still use the single tail to tell the directionality. An impact of 20o, a stain tends to have a tail accompanied by a detached satellite. When combined with stain’s long axis, the path of travel of the droplet can be indicated.

Question 2

The point of convergence that is also occasionally referred to as area of convergence is essentially the point to which the projection of a bloodstain pattern can be done accurately (Wonder, 2014). In the blood spatter analysis, this point is usually determined or established by tracing several well-defined bloodstain’s long axis within the whole pattern back to a common source or point. However, recent time have seen large debates on whether there is one “single point of convergence” and perhaps this is why the term “area of convergence” is more commonly used these days. Experts argue that the blood drops are usually distributed away from the area of impact (Wonder, 2014). However, the blood drops usually travel in various paths that cannot in real sense lead to one singular point (Wonder, 2014). The argument is that there are no two incomprehensible fluid drops that can actually originate from one single point, and this is why the point of convergence is a subject of intensive discussion. As mentioned, the more accepted term for this aspect in modern days is the “area of convergence”.

Question 3

The area of origin refers to the area with a three-dimensional space where the source of the blood was located or situated ate the exact time of the incident that led to the bloodletting. The area of convergence is part of the area of origin. The area of origin can be determined by using BPA softwares although currently, there are other mathematical methods that can be used with one of them being the tangential method. Normally, the actual impact site will lie somewhere perpendicularly above the area of convergence. Determining this involves measuring the length and width of the blood stains (White, 2010). This then allows the calculation of the angle at which the stains landed. The angle of impact’s sine can be approximated by the ratio of the width calculated to the length (White, 2010). Using a length of a string and a protractor, these angles can then be projected from the blood strain to the perpendicular, and this defines the area of origin (White, 2010). The determining of the area of origin extremely useful as it allows the investigators to determine the positioning of the victim, that’s is whether he or she was standing, sitting or lying down. These details can be used to make out the exact context of the bloodletting incident.

References

Bevel, T., & Gardner, R. M. (2008). Bloodstain pattern analysis with an introduction to crime scene reconstruction. CRC Press.
White, P. (Ed.). (2010). Crime scene to court: the essentials of forensic science. Royal society of chemistry.
Wonder, A. Y. (2014). Bloodstain Patterns: Identification, Interpretation and Application. Academic Press.