Forensic Science

Forensic Science

Forensic Science refers to the application of techniques and principles of science in the legal settings. Forensic science deals with the collection, examination and analysis of circumstantial evidence in crime scenes or other matters about law to create an association of a suspect, victim, and the place. The association of the three elements named above requires the application of scientific principles that have been tested and acknowledged per standards such as Daubert or the Frye. The application of the scientific methods requires the use of probability to give the weight of the evidence examined. Once a forensic scientist examines a crime scene, they present their evidential analysis in a court of law in the form of expert opinions. Moreover, cases requiring explaining the matter of the case to the jury may require a forensic science rather than in presenting evidence.

The issue of forensic science in investigations ranges from simple crime scenes to complex scenes such as homicide and sexual assaults. The analysis of crime scenes depends on a comparison of crime scene samples and the reference samples collected from a victim, suspect or the crime scene. It is because of this fact that the pioneers of forensic science the discipline to be a science of comparison (Bell, 2008). The comparison of the evidence uses Edmund Locards principle that if any two objects come into contact, there is an exchange of materials between them. The approach for any given crime scene follows a different approach depending on the circumstance of the crime but using the same principles. In examining the role of forensic science in investigations, this paper uses a crime scene case study. In achieving this, the paper considers the history of forensic science and the primary development in the principle. The paper then applies forensic principles and techniques to evaluate the crime scene.


History of Forensic Science

According to Houck and Siegel (2009), forensic science date back to the 5th century. However, only forensic medicine was highly practiced during those times (Houck & Siegel, 2009;Tilstone, Savage & Clark, 2006). Forensic toxicology was the first branch of the principle to be applied in investigations with Mathieu Orfilla making a significant contribution to it. Primary developments in the principle occurred during the 18th and 19th century. Several significant developments markeed the evolution of forensic science discipline. Houck and Siegel (2009)  argue that one of the mileage developments in the discipline was the development of bertillonage system, also called anthropometry. This system involved fingerprinting of a person’s physical features. Enter Alphonse Bertillon developed the system. The system was well acknowledged initially before its discredition on issues of reproducibility. Sir Edward Henry later clarified the method of anthropometry. Henry devised the modern fingerprint classification that is currently used in forensic investigations.

Another breakthrough in Forensic science involved blood typing. Some of the commonly used blood typing techniques are those of crystalline tests that are used to characterize blood. Ludwig Teichmann developed These tests in 1853 (Siegel & Mirakovits, 2013). Moreover, Schonbein developed a presumptive test on blood. Later, Karl Landsteiner introduced the use of blood in investigations in 1900 (Houck & Siegel, 2009). Landsteiner developed the ABO blood grouping system. This discovery opened consecutive discoveries of crucial importance to forensic science. For instance, it created a platformfor discovery of antigens systems such as the Lewis and Rhesus. Blood typing was discovered that allowed partial discrimination of people is dependent on these classifications.

Elucidation of the structure of DNA by Watson and Crick in 1950’s was another landmark in forensic science. This discovery formed a platform for the development of DNA fingerprinting. Sir Alec Jeffries developed this technique in 1984 (Houck & Siegel, 2009). Jeffries work is the base for DNA technology applied in forensic science. Karry Mullis developed the polymerase chain reaction, which is a core technique in forensic, in 1980’s.

According to Houck and Siegel (2009), the 20th century saw the introduction of comparison microscope in forensic science discipline. Goddard popularized the technique. The introduction of comparison microscope revolutionized the analysis of the trace evidence such as cartridges, hairs, and fibers.

Crime Scene Investigation: Case study of Miss Mary’s Sexual Assault

Crimes greatly vary and can occur in different settings and locations (Liu, 2009). The diversity if the crime scenes make it difficult for their classification. One of the classification usually used involves classification of crime scene into primary or secondary. The primary crime scene refers to the original location ,at which crime initially took place. On the other hand, secondary crime scene refers to any other place at which a subsequent crime scene occurs. A crime scene may also be referred in terms of their size. In this case, crime scenes are referred as being macroscopic or microscopic in nature. The macroscopic crime scene covers larger spatial element while the microscopic crime scene occupies smaller spatial distribution.

Often, forensic scientists are required to investigate crime scenes. According to Liu (2009), the role of forensic science in crime scene investigation is to recognize, collect and preserve physical evidence. Moreover, forensic is involved with the analysis, interpretation and presentation of physical evidence in a court of law. Houck and Siegel (2009) argue that the crime scene is the basis for any forensic work. Therefore, it is essential to conduct a thorough and effective crime scene evaluation. Moreover, careful crime scene evaluation is required because its evaluation involves a process of destruction of the evidence itself and hence subsequent evaluation of crime scenes are not considered legible in a court of law.

Crime scene investigation requires a chronological examination of the scene. According to Liu (2009), following a proper plan while investigating a crime scene is essential in ensuring that all the physical evidence is collected and properly documented. Such a process allows for crime scene reconstruction and its associations with the victim and the suspect. Inman and Rudin (2000) explains that the best procedure involved in crime processing is one that follows the chronology of evidence recognition, collection and analysis. Moreover, it involves interpreting it before its presentation in a court of law. The process of evidence collection, as mentioned earlier, forms the basis of the investigation. Therefore, it is essential to ensure that this step is carried out in a careful and holistic manner. This step requires prior preparation that involves identification of the possible evidence expected in a crime scene. The evidence is then collected starting with the one that is likely to be damaged easily until the most robust and lasting one (Houck & Siegel, 2009). The evidence is then analyzed using relevant techniques before its analysis. In elucidating the process of crime scene investigation, a sexual case study is conducted.

Case Study:  He wouldn’t turn me loose: The sexual assault case of 96-year-old Miss Mary

This case involved Miss Mary and her grandson Billy (Films Media Group, 2012). Moreover, the case also involved Susan, the wife to Billy. Billy and Susan exploited and mistreated Ms. Mary. They used Mary’s money for their personal expenditure. Trying to keep out of a nursing home, Mary did not have any option rather than to be submissive to their demands and misdeeds. Regarding this, the grandson and his wife would misused her money with Susan using her burial allocation. She would also clean for her grandchildren.

The misdeeds against Ms. Mary unraveled when Billy decided to rape her. One evening, when Billy’s wife had gone, he went home drunk and decided to rape his grandmother (Films Media Group, 2012). Ms. Mary tried to repel the rape by her grandson, whom she did not recognize, but without success. In a struggle to prevent him, Mary was injured in several regions as Billy dragged her around in the various rooms of their house. As a result of the dragging, Ms. Mary suffered several injuries. Some of the injuries involve lacerations on the wrist and the ankles. Moreover, she had bruises due to high impact from her grandson’s grabbing. Moreover, Mary suffered to a vaginal laceration due to the sexual assault by her grandson. The crime occurred about six hours from about 6 PM. After the assault, Billy had said that he will kill his grandson. However, due to his drunkenness, he slept giving Mary a chance to call the police. The police arrived the scene and arrested Billy while Mary was taken to the hospital.

The case presented can be explained using the sexual gratification theory and feminist theory (Petrak & Hedge, 2002). This theory perceives the motives of sexual harassment as being satisfaction. The offender commits the offense seeking satisfaction of his sexual desires. In the case of Mary, Billy can be said to assault his grandmother while seeking sexual satisfaction because his wife was not around. On the other hand, the feminist theory perceives the offender as committing the rape as a way of expressing control and power over the victim. In Mary’s case, she was frail compared to Billy. Billy and Susan knew that he had control over Mary. Therefore, Billy committed the assault on the account that he would easily manipulate her.

According to Berlin (2011), the fourth amendment entitles a person to a right to security in their persons, papers, houses and effects against seizures and searches. However, the provision may be violated in the probable case. However, this violation requires affirmation and the description of the location of search and the thing or person to be searched. In the case of Mary’s case, she called for help from the police force. Therefore, this description allowed for the violation of the fourth amendment. Consequently, there was no fourth amendment issue that required to be solved while visiting Billy’s house.

Houck and Siegel (2009) states that the initial response of the case would be to secure the scene. This process involves the establishing a perimeter of the regions that may provide indispensable evidence and other relevant evidence. In the case of Mary, the initial process would be to secure the house and the outside region where the dragging occurred. A preliminary survey would then be conducted to identify evidential artifacts in the outside. The examiner should then prepare them for the examination. Preparation requires understanding the circumstance of the scene such the sexual assault in the case of Mary and identifying the probable evidence that might be present in the scene.

After preparation, the examiner ought to then prepare a note of what is observed and the implication of the surrounding. Sketches would also be essential in the case due to the areas showing characteristics of dragging (Houck & Siegel, 2009). The sketches will also help to show areas showing possibilities of struggle. The scene should then be captured from an outside to inside approach. The bruises on Mary should also be captured. However, photographing Mary could be done at the hospital. A detailed search on the scene should be conducted to identify all the evidential artifacts. This step would be followed by the collection of the evidence using the relevant methods, it’s packaging, documentation, and preservation. During the whole process of scene examination, it is essential to ensure that a chain of custody is observed.

Vaerious controversies face the case of Mary duew to matters of relationship victim and the suspect. However, some evidential artifacts would be essential in solving the case. Some of the evidence types that could be collected in the case includes such semen, fingerprints, blood, saliva, hair and epithelial cells. This paper consider semen, blood, and epithelial cells.

Seminal evidence could be collected from the surrounding and bedding from Mary’s bed. Moreover, a vaginal swab by a relevant female medical examiner on Mary could be used to collect seminal evidence. During the crime, Mary claimed of being assaulted. Therefore, it was possible to obtain epithelial cells from Billy and Mary, especially from their fingernails. In one instance, Mary claimed that Billy had entered his fingers into her nostrils scratching. It was, therefore, possible to obtain swabs from Billy’s fingers to obtain epithelial cells that could be essential in collaborating her allegations. During the crime, Mary had suffered various bruised and lacerations causing her to bleed. Consequently, blood samples could be obtained from both Mary and Billy and the surrounding.

Blood evidence should be collected using an EDTA paper (LeBeau & Mozayani, 2001). Swabs should also be collected for presumptive and confirmatory tests. The analysis of the blood evidence would involve conducting a presumptive test that would be followed by a confirmatory test. According to Becker and Dutelle (2013), the presumptive test that can be done is such as the luminol and phenolphthalein tests. On the other hand, the confirmatory test involves the precipitin and the Teichmann test (LeBeau & Mozayani, 2001). Once blood sample has been ascertained, it can be analyzed for DNA typing using such as Polymerase Chain Reaction. This procedure is done after extracting DNA from the blood. A similar analysis would be performed in the case of semen. However, the semen would require differential DNA extraction. Consequent DNA profiles would enable to infer their genetic origin. The presence of mixed DNA profile would infer that there was a possible exchange of materials. More weight of evidence will be associated with such occurrence of DNA profile in the case of semen if it is associated with Billy’s reference sample.

The samples collected from Billy’s fingers, and from Mary’s body would also have collaborative value in the case. The epithelial cells collected would be used to extract DNA that is then used to generate a profile (LeBeau & Mozayani, 2001). The presence of Mary’s DNA profile in the crime samples collected from Billy’s body would help to ascertain Mary’s allegation of the occurrence. Consequently, the facts elucidated would help dispute the defendant’s case that the case was a probable hallucination event. The presence of Billy’s DNA profile from the samples collected from Mary’s body would further help to ascertain similar facts.

Forensic science is an indispensable tool in crime investigations. The discipline allows the association of a suspect, victim and the crime scene using comparison. Forensic science uses techniques that have been tested allowing for the reproducibility of results obtained and hence creating assurance on either party of the case and the juror. The discipline can also be applied in diverse cases. In the case of this paper, we have considered the application of forensic science in determining the circumstances of a case of sexual assault. In this case, Forensic allows for the generation of information that supports the allegation by Mary by disputing chance of occurrence of the assertions by the defense.




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