Free Essay: Species Testing and Components of Blood Useful in Forensics

Species Testing

It is of critical importance for wildlife forensic experts to be able to determine species of species from the products associated with the particular species. With the increased number of endangered species ever growing and most criminals preferring to reduce their conquest to smaller undetectable amounts, this will go a long way in stopping the vice. As early as in the 1980s the ingenuity of such methods was in practice (Weir, 2004). In one case, a man was sentenced to two years in prison for selling eggs of an American paddlefish. Testing done by the wildlife scientists confirmed that the eggs were not of a Russian Sevruga as labeled by the man who owned a caviar company. The man was also fined $50,000 in addition to the prison time while his caviar company had to part with $150,000 (Gale, 2005). Species identification is a possible breakthrough by which poachers and illegal hunters can be netted and stopped from killing endangered species(Gomes, Kohlmeier & Schneider 2011, 469).

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Components of Blood Useful in Forensics

Blood forms a significant portion of serologically vital body fluids. Forensic science has made it possible to acquire a lot of information even from minute amounts of blood (Saferstein, Meloan & James, 2014). By analyzing the morphology of blood stains as well as chemical characteristics, it is possible to exonerate or pinpoint the victim and the perpetrator. It is a known fact that blood is the most common physical evidence found in crime scenes, especially in violent crimes (Odoardi, Anzilloti & Strano-Rossi 2014, 63).

Red blood cells

The blood component responsible for the transfer of respiratory gases to enable gaseous exchange. The cells lack a nucleus and contain protein antigens called agglutinogens on the surface of the membrane (Gomes, Kohlmeier & Schneider 2011, 470). The most significant protein for forensic science in erythrocytes is the hemoglobin. The heme component of hemoglobin gives the color observed in erythrocytes. Therefore, the presence of the heme molecule is a marker for the presence of blood (Chen & Hortin 2000, 235).

The characteristic color of blood associated with heme is an essential aspect for forensic scientists. It makes it possible for blood spatter analysis which can give investigators vital information about the crime such as the weapon used, the manner of wielding the weapon, and even the character of the perpetrator (McClintock, 2014). Pattern analysis of blood has proved a significant step in recognition of suspects and interpretation of the sequence of events (Bailey, 2015, 132).

Formation of blood stains is due to dehydration of red blood cells which causes them to shrink and change shape. This phenomenon can find usefulness in identifying the freshness of the blood and thus the approximate time it was spilled, depending on the prevailing weather condition (McClintock, 2014).

Heme component is also the basis for many presumptive tests that have been formulated for presumptive identification of blood (Tobe et al., 2007, 102). The catalytic blood tests carried out on the blood is usually depended on oxidation and reduction chemical processes. Heme group has a characteristic peroxidase-like activity which in the presence of hydrogen peroxide acts as a catalyst enabling the breakdown of hydrogen peroxide to water and an oxidizing agent. Phenolphthalein, luminol, fluorescein, o-tolidine and many other compounds for presumptive tests are useful in this way (Reddy 1997, 16; Gunn, 2011). The reaction for such compounds occurs in such a way that the end product has a different color from the initial one, and thus because the color appears as a result of a reaction, it is a confirmation for the presence of peroxidase and consequently heme. Even minute traces of heme can act as a catalyst and elicit color change (Li, 2015; In Zinn & Dintwe 2015, 47). However, the tests suffer from false positives which can occur due to the presence of peroxidases, metallic salts, catalases, cytochromes and other stronger oxidants (In Zinn & Dintwe 2015, 47).

Electrophoresis is also a possible method for identification of heme group. Hemoglobin proteins are said to be conjugated thus in the required PH they electrophores in a support medium towards the oppositely charged electrode where they are stained by catalysis method to form a color. Bands of color so formed are then compared with known standards (Carey & Mitnik, 2002, 1395).

Another important aspect of blood hemoglobin is that being a protein; its detection can be by anti-hemoglobin precipitin. The reaction is highly specific and is the confirmatory test for human blood (FBI, 2012). This test is carried out through a diffusion process which can be one dimensional or two dimensional. Immunological tests can be used in such a way for blood proteins. An animal is injected with blood proteins of human origin, and the corresponding immune reaction against the human protein antigen is extracted and purified (Advenier, Paris & Piaton 2018 1049). The antibody so produced can react against the human antigen both in vivo and in vitro. In the presence of the antigen, the antibodies react to form a complex, a culmination which can signify the presence of blood (Gaensslen, 1983; McClintock, 2014). The antibodies have very high specificity and can only identify the specific protein which elicited their production. Thus the method can be used not only for confirmation of the presence of blood but also for species confirmation (Zapata, Gregorio & Garcia-ruiz, 2015).

Antigens on Erythrocyte Membrane Surface

Other blood components that are utilized in forensics are the antigens present on erythrocytes surface. The surface antigens are commonly used in ABO blood typing and other forms of blood typing (Zachova et al., 2004, 44). Individuals with Antigen A are categorized as belonging to blood group A. Blood group B individuals have B antigens, blood group AB has both antigens A and antigen B whereas those with neither antigens belong to blood group O (Watson 2013, 385; Virkler & Ledney, 2009, 1).

The rhesus antigen has also found use in forensic science. Rhesus negative individuals have no rhesus antigen whereas those with the antigen are classified as rhesus positive (Watson 2013, 377). Blood at the crime scene can be tested for blood group to identify whether it came from the victim, from the assailant or both. With this information, the number of suspects in a case can be significantly reduced, and the facts of the case can be determined. With this evidence, the prosecution can then be adequately armed to prosecute a case with a suspect firmly on their grip (Advenier, Paris & Piaton 2018 1049).

White Blood Cells

A bloodlet of human blood contains an average of 7,000-25,000 white blood cells (Virkley & Ledney, 2009, 3). The white blood cells structure consists of nuclei and can thus be used in forensics in the identification of a suspect by creating a DNA profile. DNA is the genetic material coding for the unique characteristics of a particular person. This characteristic makes it easy for forensic experts to put a suspect at the scene of a crime or to exonerate a suspect. Since the DNA information is unique to each, a laboratory technique known as DNA fingerprinting is needed to identify whose blood was present at the scene (Sikirzhytskaya et al., 2013, 1141; Waye et al., 1991, 1198; Butler, 2009). The experts need only a few DNA molecules from which DNA amplification can be done by polymerase chain reaction (PCR) to replicate the sample (NCIDS, 2018; Alaska Scientific Crime Detection Laboratory-ASCL 2018, 17). The sample can then be used to conduct as many tests as may be required to enable solving of the crime (An et al., 2012, 545; Saks & Koehler 2008, 199).

Serum

Blood serum can find a lot of usefulness in a wide range of forensic analyses due to the presence of several biologically significant components. Blood serum is not only found in blood but also in the lymphatic system circulation. Serological forensics have found that it can aid in identifying poisons and other drugs in corpses. Detection of antibodies for particular infectious agents can also be done through serum (An et al., 2012, 547; Mirza, 2018).

Isoenzymes

Isoenzymes are essential for genetic marking. There exists a wide range of enzyme forms which if utilized correctly can be of great use to forensic science (Sikirzhytskaya et al., 2013, 1144; ASCL 2018, 20).

Phenotypic Frequencies

Individualization of blood types involves proteins and enzymes. A look at enzymes and blood proteins shows that they are polymorphic or isoenzymes. Therefore, their existence takes several forms and variations (Michalski et al., 1986, 586). From the table below we can calculate the population percentage expected to have blood type: ABO group B + EAP subtype CA + Hp subtype 2-1 + ADA subtype 1 + AK subtype 2-1+ and PGM subtype 2-1.

Phenotypic Frequencies For a Given Population

% of Population with the blood type:

0.12 0.0250.52609040.0870.373

=0.04629%

References

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Odoardi, S., Anzillotti, L. and Strano-Rossi, S., 2014....