Blood evidence in forensic investigations: a literature review

Blood evidence collection and sampling has always been an important topic. The subject has been idealized and glamorized by entertainment shows like CSI and others. However, the field is not as easy and basic as it may seem and the field is indeed complex and a large amount of work that absolutely has to be done right the first time so as to preserve convictions and other legal events or standards. The attached documents will look into scholarly articles relating to blood sample evidence and the field at large. What the data means for the wider criminal justice and scientific communities will also be summarized.

Blood Evidence

Blood evidence has become more and more of a prominent facet of crime investigations that in any way involved blood. This can include the form of blood splatter patterns, whose blood is where in general, how blood does or does not place people at the scene, where the blood is not present and how long it has been there. Also important is the evidence chain including chain of custody, how the evidence was collected, how it was analyzed and truly how definitive the evidence is as it relates to proving a criminal case. While blood alone does not typically make or break the case for a district attorney and/or a crime lab, it can absolutely be a deal-breaker if done incorrectly.

Analysis

The author of this report chose blood evidence because DNA and spatter patterns are a huge part of the investigation of crime scenes. Even non-violent crime prosecutions can hinge on blood evidence including placing someone at a scene or when a certain event such as the death or a victim or the timing of a wound. Quite often, cases are largely circumstantial in nature and blood evidence can help at least somewhat clarify what occurred and when even if no eyewitness or video evidence of a timeline exists. The author of this report sought out for works on the subject of blood evidence in a crime scene setting and found four in particular that have strong implications on the subject.

The first such work relates to the chronicling of a crime scene investigator's life. The investigator even weighs in on some of the more seminal cases of the recent years and decades that have involved blood evidence. One such case, and perhaps the most notorious criminal case of all time, was the OJ Simpson case. The author also shares how blood spatter can reveal a lot about what happened and how it happened (Giardino & Drake, 2010). Speaking of timing of blood spatter and so forth, another major component of the investigation of that topic is the age of the blood drops that are dropped at a crime scene or any other area where a criminal or victim may have been. This particular report covers how blue spectral shifts can be used to assess the hemoglobin band of a blood sample and thus establish the age since deposition of the stain (Hanson & Ballantyne, 2010).

Sometimes, blood stains can blend with other areas of crime scene investigation including fingerprints. Many times, a victim or criminal will leave a fingerprint that is contained within a stain and quite often it is in blood. Unlike water or other substances, a fingerprint can quite easily be visible in a blood stain after it dries. As such, the stain would have to be assessed to decipher both whose print it is and who the blood belongs to. The two may be one and the same or they may be different. It entirely depends on the composition of the scene, where the stain was found and what actions and behaviors led to the stain being deposited (Becue et al., 2011). The fourth and final article reviewed for this report covered DNA evidence and how persuasive it can be in a trial. While DNA is often deemed to be exhaustive, it is not a proverbial smoking gun. It can place a person at a crime scene and it can also indicate that sexual activity occurred but presence of blood or other bodily fluids alone does not prove a case. For example, a person being at a crime scene is not a major revelation if the person lived there or was intimate with the victim or if the victim was simply where the alleged perpetrator would normally be. Similarly, blood and/or other fluids found post-coitus are not alone proof positive that the act was forced, just that it occurred. Other times, however, blood evidence tying a person to a scene can be extremely important because perhaps the victim had no business for being in a certain place and/or they cannot explain why they were at said place. Generally, blood evidence and DNA is very convincing but it is not a fix-all for prosecuting attorneys.