Body Fluid Identification in Forensics - Literature review Example

Body Fluids The process related to the immediate identification of body fluids at the crime scene is considered to be a vital aspect of forensic science. In fact, the ability to establish whether or not there are body fluids present and consequently, determining it provides a sample that is later subjected to a series of laboratory tests that extends to DNA analysis, which is deemed to be a fundamental step in a great number of investigations (Virkler & Lednev, 2009). It is crucial to note that in some cases, the capacity to identity a fluid could be enough to influence the overall outcome of a given case. However, for most cases, this is not considered an easy task given that most of the body fluids stains are either invisible to the naked eye or might be similar in their attributes when compared to other forms of fluids or substances for that matter. Even in cases whereby the identity of a given stain could seem s direct and obvious for a forensic investigator, there is always a need for absolute confirmation so that there is easier provision of evidence that can be used in court to make a prove or disapprove an underlying case especially in those cases that have a possibility of occurrence mixtures (Virkler & Lednev, 2009). There is also a high likelihood of a stain containing a multiple number of body fluids belonging to more than a single victim. Physical tests that are conducted on stains provide a platform for crime scene investigators and laboratory technicians to establish a fluid or engage in the confirmation of the absence of one fluid hence presenting an equal value within a given case. It is important to note that the most common forms of body fluids that are found at the crime scenes include; blood, saliva and semen. However, in other cases, there are possibilities of others like vaginal fluid, urine and sweat being used in different purposes of an investigation that include; provision of valuable DNA evidence (An, Shin, Yang, & Lee, 2012). Notably, it is established that most of these fluids can be subjected to a either a single or more screening tests that are deemed to be presumptive in nature as some of them have confirmatory set of tests that would extensively be able to identify their presence in a donor. The major problem with these tests lies with the destruction of underlying sample. There is a likelihood of a case being explored and closed with just a small presence of biological evidence and thus, there is a great need to have these small quantities examined in a more efficient manner by way of non-destructive methods in order to protect underlying DNA evidence (An, et al, 2012). Another notable disadvantage of the current methods lies in the fact that they are formulated for purposes of detecting a particular body fluid hence the investigator is called upon to make clear decisions on which tests to execute based on the fluid that will likely be considered to be present within a given sample. Following this line of argument, there is a definite need for a universal confirmatory test that should be applied to any given specific stain that can be used to establish any of the body fluids that could be present within a given sample. Body Fluids & Current Identification Techniques It is crucial to note that each of the underlying body fluids possess a specific unique composition and the presence of particular components within any single fluid in comparison to another forms a fundamental platform for identification (Jobling & Gill, 2004). A. Blood Blood is one of the most common forms of body fluid that is usually encountered in crime scenes. Forensic investigators use both presumptive and confirmatory tests in its identification process. One of the simplest tests that any crime scene investigator can adopt for the purpose of detecting bloodstains which are not clearly seen rest with an alternative light source(ALS) like the ultraviolet light (Jobling & Gill, 2004). The method is considered to be effective especially in cases whereby the stains is present on a dark background. ALS could be used to direct attention to a given latent stain that is found within a crime scene and later, presumptive tests carried out in order to develop a great deal of conclusions in relation to the body fluids that are present in a stain (Jobling & Gill, 2004). Poliligght is one tool that can be used to ascertain the presence of stains that is covered with materials like paint. Notably, the luminol test is one of the well-known presumptive blood tests that crime specialists adopt. It is focused on establishing the capacity of haemoglobin as well as possible derivatives of blood to result to an oxidation of luminol in the immediate presence of alkaline solution. A presumptive blood test forms the basis for confirmatory tests like crystal tests; microscope tests as well as spectroscopic tests. B. Semen The most known presumptive tests for semen involve ALS that uses ultra-violet light. The process related to searching for semen in a crime scene involves simple and non-destructive approaches. For most cases, a Wood Lamp or Bluemaxx BM500 is used for testing purposes (Jobling & Gill, 2004). Another presumptive test involves the test for the presence of choline under the Florence test. The most widely-accepted confirmatory test for detection of semen is the microscopic identification of sperm cells with Christmas tree stain being used for stain identification purposes. C. Saliva Just like blood and semen saliva can also be detected using the ALS approach. Saliva stains appears b bluish-white under ultra-violet light (Virkler & Lednev, 2009). Another presumptive test used for its identification lies on the underlying activities of amylase so that two definite forms can be formed within the overall human body as a whole. D. Vaginal Fluid This body fluid plays a significant role in proving a sexual assault case. There are currently not many techniques used to test this stain since it has not been effectively defined overtime. There is a high possibility of its components changing on the basis of menstrual cycle of the female and this could result to testing of specific components extremely challenging. One of the most known tests is glycogenated epithelial cells while using a periodic acid-Schiff (PAS) reagent (Virkler & Lednev, 2009). Another approach would involve enzyme that is known as vaginal peptidase that is mostly found within vaginal fluid samples. Certainly, the investigators could adopt an approach whereby the ratios of the lactic and citric acids that are the components of vaginal fluids is analysed to the ratios that are present within semen in order to ascertain the presence of vaginal fluid either by itself with a specific mixture. Proteins & Amino Acids Proteins are a set of complex and organic-based compounds that is made up of a good number of acids connected together through peptide bonds while still being cross-connected between chains using sulfhydryl, hydrogen bonds as well as van Waals forces (Uauy et al, 2016). It is important to note that there is a great deal of diversity present within the chemical composition within proteins when compared to any given group of biologically active compounds (Uauy et al, 2016). Proteins can be successfully categorised into; first, simple proteins, which when subjected to hydrolysis process yields to amino acids and some occasions small carbohydrates. Good examples of simple proteins include; albumins and glutelins. Secondly, there are conjugated proteins, which are basically simple forms of proteins that are connected to some non-protein materials within the body. A good example of conjugated proteins include; haemoglobins, nucleoproteins as well as glycoproteins. Finally, there are derived proteins, which are possibly derived from either simple or conjugated forms of proteins or even by way of chemical means. Good examples of these proteins include; denatured proteins as well as peptides (Uauy et al, 2016). Structure of Proteins The underlying possible configuration of protein molecules is established to be indeed a complex affair given that a good number of protein molecules can be designed and developed and is mostly present within most of biological matter portraying different forms of physical attributes (Uauy et al, 2016). Most of global types of proteins are mostly present with blood and tissue fluids in amorphous globular design with thin and non-existent forms of membranes. It is important to ascertain that most of the collagenous proteins are present within connective tissues like skin or even cell membranes. Notably, fibrous proteins are mostly present in such matters as hair and muscle (Uauy et al, 2016). Crystalline proteins are mostly exemplified by use of lenses of the eye and other related tissues. Enzymes are forms of proteins that portray a specific chemical functionality while also mediate a great number of physiological processes in life. In most cases, numerous polypeptides play the role of hormones in tissue systems that provide control on a set of different chemical or physiological processes. Amino Acids Amino acids are known to be the fundamental building blocks of proteins with more than 20 types of amino acids having been separated from existing natural proteins. It is important to ascertain that animals are not able to produce own amino acids hence they can only obtain it from diet (Uauy et al, 2016). Amino acids mostly share a basic fundamental structure that is made up of central atom which is fairly-known as alpha carbon that is linked together to a specific amino group NH2, a carboxyl group (COOH) as well as an hydrogen atom as shown below; At a physiological pH, amino group is mostly protonated and is made up of a distinctive positive charge while on the other hand, a carboxyl group is mostly deprotonated and would possess a negative charge. Each of the amino acid would certainly be linked to an atom or groups of atoms to a central atom in a process known as the R Group (Uauy et al, 2016). R group focuses on determining the possible identity of a given amino acid. For instance, in the event that R group is established to be a hydrogen atom then the amino acid would be glycine. Protein Quantitation Ultraviolet (UV) absorbance at 280 nm (range: 0.1-100 ug/ml): Such amino acids as tyrosine as well as tryptophan provides proteins with an attribute of ultraviolet absorption spectrum at 280nm, which is mostly utilised for the purpose of estimating overall protein concentration. This assay has a detection limit of 0.1-100ug/ml. it is affordable; rapid and consumes a relatively smaller amount of sample volume (Lo, 2015). However, it is mostly incompatible with both detergents and denaturation agents. Bicinchoninic Acid (BCA); is an absorption rate of 562nm and operates under a mechanism characterised by copper reduction as well as BCA reaction with Cu 1+. It enjoys a detection limit of 20-2000 ug/ml (Lo, 2015). It is compatible with detergents and denaturing agents and low variability position. However, it has low or even compatibility mechanisms with reducing agents. Bradford Assay; has an absorption rate of 470nm and its mechanism is characterised by a sophisticated formation between Coomassie brilliant blue dye and proteins. It enjoys a detection limit of between 20-2000 ug/ml (Lo, 2015). Its pros are that it is compatible with reducing agents and it is rapid. However, it is somehow incompatible with detergents. Lowry Assay; has an absorption rate of 750nm with its mechanism characterised by a copper reduction by proteins. It has a detection limit of 10-1000 ug/ml (Lo, 2015). It enjoys a great deal of sensitivity and precision. However, it is certainly incompatible with detergents as well as reducing agents. Nanodrop spectrometry is mostly adopted for the purpose of assessing DNA or thereby protein concentration within a given level of sample (Jobling & Gill, 2004). The Nanodrop Spectrophotometer will always come with software which will provide the details about the concentration of DNA/RNA or even protein sample. It further has numerous models of specific protein assays or even bacterial concentration. References An, J. H., Shin, K. J., Yang, W. I., & Lee, H. Y. (2012). Body fluid identification in forensics. BMB Reports, 45(10), 545-553 Jobling, M. A., & Gill, P. (2004). Encoded evidence: DNA in forensic analysis. Nature reviews. Genetics, 5(10), 739. Lindenbergh, A., de Pagter, M., Ramdayal, G., Visser, M., Zubakov, D., Kayser, M., & Sijen, T. (2012). A multiplex (m) RNA-profiling system for the forensic identification of body fluids and contact traces. Forensic Science International: Genetics, 6(5), 565-577. Lo C, Kays I, Emran F, Lin T, Cvetkovska V, & Chen B. (2015). Quantification of Protein Levels in Single Living Cells. Cell Rep.13, 2634-44 Uauy, R., Suri, D. J., Ghosh, S., Kurpad, A., & Rosenberg, I. H. (2016). Low circulating amino acids and protein quality: an interesting piece in the puzzle of early childhood stunting. EBioMedicine, 8, 28-29. Virkler, K., & Lednev, I. K. (2009). Analysis of body fluids for forensic purposes: from laboratory testing to non-destructive rapid confirmatory identification at a crime scene. Forensic Science International, 188(1), 1-17 Read More

Body Fluids & Current Identification Techniques It is crucial to note that each of the underlying body fluids possess a specific unique composition and the presence of particular components within any single fluid in comparison to another forms a fundamental platform for identification (Jobling & Gill, 2004). A. Blood Blood is one of the most common forms of body fluid that is usually encountered in crime scenes. Forensic investigators use both presumptive and confirmatory tests in its identification process.

One of the simplest tests that any crime scene investigator can adopt for the purpose of detecting bloodstains which are not clearly seen rest with an alternative light source(ALS) like the ultraviolet light (Jobling & Gill, 2004). The method is considered to be effective especially in cases whereby the stains is present on a dark background. ALS could be used to direct attention to a given latent stain that is found within a crime scene and later, presumptive tests carried out in order to develop a great deal of conclusions in relation to the body fluids that are present in a stain (Jobling & Gill, 2004).

Poliligght is one tool that can be used to ascertain the presence of stains that is covered with materials like paint. Notably, the luminol test is one of the well-known presumptive blood tests that crime specialists adopt. It is focused on establishing the capacity of haemoglobin as well as possible derivatives of blood to result to an oxidation of luminol in the immediate presence of alkaline solution. A presumptive blood test forms the basis for confirmatory tests like crystal tests; microscope tests as well as spectroscopic tests. B. Semen The most known presumptive tests for semen involve ALS that uses ultra-violet light.

The process related to searching for semen in a crime scene involves simple and non-destructive approaches. For most cases, a Wood Lamp or Bluemaxx BM500 is used for testing purposes (Jobling & Gill, 2004). Another presumptive test involves the test for the presence of choline under the Florence test. The most widely-accepted confirmatory test for detection of semen is the microscopic identification of sperm cells with Christmas tree stain being used for stain identification purposes. C.

Saliva Just like blood and semen saliva can also be detected using the ALS approach. Saliva stains appears b bluish-white under ultra-violet light (Virkler & Lednev, 2009). Another presumptive test used for its identification lies on the underlying activities of amylase so that two definite forms can be formed within the overall human body as a whole. D. Vaginal Fluid This body fluid plays a significant role in proving a sexual assault case. There are currently not many techniques used to test this stain since it has not been effectively defined overtime.

There is a high possibility of its components changing on the basis of menstrual cycle of the female and this could result to testing of specific components extremely challenging. One of the most known tests is glycogenated epithelial cells while using a periodic acid-Schiff (PAS) reagent (Virkler & Lednev, 2009). Another approach would involve enzyme that is known as vaginal peptidase that is mostly found within vaginal fluid samples. Certainly, the investigators could adopt an approach whereby the ratios of the lactic and citric acids that are the components of vaginal fluids is analysed to the ratios that are present within semen in order to ascertain the presence of vaginal fluid either by itself with a specific mixture.

Proteins & Amino Acids Proteins are a set of complex and organic-based compounds that is made up of a good number of acids connected together through peptide bonds while still being cross-connected between chains using sulfhydryl, hydrogen bonds as well as van Waals forces (Uauy et al, 2016). It is important to note that there is a great deal of diversity present within the chemical composition within proteins when compared to any given group of biologically active compounds (Uauy et al, 2016).

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