Sample Essay on Forensic Investigation

Forensic Investigation

Forensic biology is vital in this case because it will be used to know the time since the death of a person. After death, the human body decomposes in different stages; each stage of decomposition has its unique biological characteristics which can be used to estimate the time since death. Each stage of decomposition has its unique characteristics whereby different types of insects arrive, and unique biological changes to the body occur. “Blowflies lay their eggs on the corpse immediately after death and move away when the body reaches an advanced stage of decomposition” (Gunn, 2009).  Activities of different biological insects on the corpse are crucial in knowing the time since the death of a person occurred. In the early stages, certain biological changes occur, for instance, cooling of blood, stiffening of muscles and a reduction in the body temperature. The presence or absence of insects is combined with other vital information scene and then used to determine the time since the death of a person.  Analysis of stomach contents is also another method of forensic biology that can also be used to estimate time of death using simple microscopic methods (Coyle, M, Cheng-Lung, Wen-YuLin, Lee & Palmbach, 2005).  Forensic biology is essential in this particular case because it will be crucial in estimating the time since death of the partially decomposed body and the skeletons that are found at the crime scene.

Mapping: This will be my first course of action when I arrive at the scene of the crime, before even stepping into the crime scene I will map the place so as to avoid entry and exit from the scene. This will help me in establishing the boundaries of the scene and preventing people from tampering with physical evidence that is vital in the investigation of the manner of death. Preserving and securing the scene of a crime is crucial because it yield clues about the dead person identity and manner of death.

I will conduct onsite identification at the scene while adhering to all rules and guidelines that govern forensic investigation. I will identify all the scattered remains as they are found. I will then set up a screening area where the partially decomposed body and the skeletons will be systematically sifted through a screen to reveal human remains, artifacts, fibers, and insects. I will then document all that I found at the scene of crime. Lastly, I will retrieve the remains properly, label them, and secure them for transportation to the forensic laboratory for further investigations.

Contamination

I will avoid contamination at this stage of investigation by adhering to guidelines, for instance, use barrier clothing when handling the freshly decomposed body and the skeletons, restrict access to the area containing the remains; clean scene examination equipment and ensure that equipment used at the scene is adequately decontaminated.  I will wear a disposable overall that will cover my hair, cloth and shoes to avoid the transfer of materials.

Controlling first responders: I will control first responders and law enforcement officers by establishing boundaries of the crime scene. I will use tapes to control entry to the place which may contaminate physical evidence. I will ensure that there are no threats to first responders; scan area for sights, sounds, and smells that endanger the lives of people around the scene of a crime. Controlling first responders and law enforcement officers provides protection for the physical evidence from trace contamination (Houck, Crispino & McAdam, 2012).

First responders and law enforcement officer pose numerous challenges to the crime scene investigator. First, they are likely to tamper with the physical evidence which may lead to wrong inferences and thus wrong conclusions. First responders can also transfer evidence from one item to another, and this may lead to contamination and thus wrongful convictions.

Identifying the remains: First, I will extract samples from the partially decomposed body and the skeletons for DNA analysis. I will compare the DNA results with those of people who have been reported to be missing. I will also examine different features that are found on the skeletons for easy indemnification. I will look the long none like the femur, others to know the stature of the person. I will finally extract samples from each of the skeletons for further DNA analysis in the forensic laboratory.

An assessment of the scene determines what kind of documentation is the most appropriate. Various methods can be used in the documentation process, for instance, photography, videoing and note taking. Photographs allow sharing of information with other agencies investigating the death, and thus, it is easy to make comparisons and arrive at a conclusion.  I will document Personal information from witnesses, victims, suspects and any statements or comments made at the crime scene. Documentation is crucial because it provides vital information to substantiate investigative considerations.

Transportation: I will package the evidence in tamper prove material for safe transportation to the lab. I will ensure that I keep the evidence dry and at room temperature. After securing the evidence, I will seal, label, and transport in a way that ensures safe delivery to the forensic laboratory. I will ensure that evidence that contains DNA is not transported in plastic bags which retain damaging moisture that might lead to contamination. The container in which each item of evidence is transported is dependent on the type of evidence (Mozayani &  Noziglia, 2011).  I will ensure that each item of evidence is labeled for features like the type of evidence, Officer responsible for the investigation, the name, rank and identification number of the officer for whom the evidence was recovered, Transporting officer before it is transported to the lab.

 

Contamination at the lab

The probability of evidence which is in liquid form mixing with other items from other scenes which are unrelated is so high in the forensic laboratory because of the conditions that are found in the place.  The increasing sensitivity of DNA analytical techniques makes it so hard to eliminate the possibility of contamination in the laboratory. Therefore, an effective DNA anti-contamination process requires a combination of approaches so as to minimize the risk of occurrence and to maximize the ability to detect contamination when it does occur. Contamination in the laboratory can be minimized in the following ways; minimizing the time that samples are held in open receptacles such as unsealed microstate plates and Minimizing the opportunity for a sample to sample transfer by keeping batch sizes manageable. Evidence that is transported to the laboratory must be sealed in tamper proof packages to prevent tampering and contamination (Pyrek, 2007).

Process of DNA analysis

DNA analysis of a decomposing body involves a lot of steps which must be all adhered to so as not to arrive at wrong conclusions. DNA  that is used in an investigation of death  can be found in blood, saliva, perspiration, sexual fluid, skin tissue, bone marrow, dental pulp, and hair follicles. DNA analysis is used in the identification of the deceased when other forms of identification do not provide adequate information. The presence of certain recognition sites in a sample generates differing lengths of DNA fragments, which are hybridized with DNA probes that bind to a complimentary sequence in the sample (Karagiozi & Sgaglio, 2005).

First I will extract samples from specific parts of the partially decomposed body. I will then separate the DNA molecules from all other cellular material that may be present in a particular biological sample then measure the sample so as to know the quantity of DNA in the sample and if it is enough to give the right results. I will then heat and cool the samples in a thermal cycling pattern for approximately 28 cycles. Lastly, I will carry out a process called capillary electrophoresis, draw inferences from the reaction and then make conclusions based on the results. I will compare the DNA results with those of persons who have disappeared and those of the relatives of persons who have disappeared so as to know the identity of the partially decomposed body. I will use a confirmatory test whereby I will want to confirm the identity of the person by comparing DNA results of relatives with those of the samples collected from the dead body.

Serology will play a crucial role in the testing process because the samples that will be used in the analysis will mostly be from body fluids. The body that is partially decomposed still has fluids that can be used as samples in which DNA can be extracted. Forensic serology involves the identification of different types of body fluids, for instance, blood, saliva, perspiration and sexual fluid. Serology is vital in the testing that will be carried out on the samples from the partially decomposed body because it is a confirmatory test which aims to confirm the identity of the deceased.

Several challenges are bound to arise during the interpretation of DNA results because of the conditions that are present in the laboratory. First, laboratory errors, for instance, wrong date entry are poses a challenge in the interpretation of DNA results. Laboratory errors may be as a result of wrong labeling and contamination of evidence. Accidental transfer of materials, errors in identification or labeling of samples, misinterpretation of test results, and intentional planting of biological evidence are the main challenges to interpretation of DNA results. Different profiles can be consistent with a mixture and thus the probability that a fluid might, by coincidence, be included as a possible contributor is far higher in a mixture case than a case with a single-source evidentiary sample thus posing a challenge to interpretation. There is also a possibility of finding a match by coincidence when searching through a database that has millions of profiles; such a match may pose a challenge to the interpretation of results. If everyone in a database is innocent, there is a probability that one person will have the match. A false incrimination can also be gotten when typing errors occur when running the results through a database of millions of profiles. Typing errors are likely to produce a false match when the results of the DNA analysis are directly compared with those that are found in a database with millions of profiles.

Facial reconstruction is the reproduction of an individual’s face from skeleton remains (Sherris, Larrabee &Larrabee, 2010).  Facial reconstruction will play a crucial role in this investigation because it will be crucial in revealing the characteristics of the deceased people. The facial appearance of the skeletons will be examined so as to reveal characteristics of the deceased, for instance, sex and race. We have differences in the thicknesses of the soft tissues of males and females of different races and thus the face of the skeleton can be used to tell the sex and the race of the deceased.

Court case scenario one

John was found guilty of killing people and dumping them at the location where the partially decomposed body and the skeletons were found. After a successful investigation process, the investigators narrowed down to John and placed him at the crime scene. Hair samples that were collected from the scene of the crime were subjected to a DNA analysis whereby they matched that one of John after the results were run a database that has millions of profiles. The partially decomposed body was examined, and it was discovered that the person was killed by strangulation. The signature of John, who is an ex-convict, was strangulation where he killed his victims by strangling them and cutting certain parts from their bodies. Investigators linked the unique signature and modus operand at the crime scene to John and thus the judge found him to be guilty as charged.

Court case Scenario two

Peter was wrongfully convicted after contamination of the evidence that was collected from the scene of the crime and a typing error by a data entry officer. A lab attendant accidentally labeled a different testable with different samples from another crime scene with the name of the above crime scene. A data entry officer missed one code when feeding the results of the DNA analysis in a database that had millions of profiles. The profile of Peter, a law abiding citizen coincidentally matched the results, and thus he was arrested and linked to the murders. The court found peter guilty just based on the DNA results and he was wrongful convicted.

References

Coyle, H. M., Cheng-Lung, L., Wen-YuLin, Lee, H. C., & Palmbach, T. M. (2005). Forensic Botany: Using Plant Evidence to Aid in Forensic Death Investigation. Croatian Medical Journal, 46(4), 606-612.Gunn, A. (2009). Essential forensic biology. Chichester, UK: Wiley-Blackwell.

Houck, M. M., Crispino, F., & McAdam, T. (2012). The science of crime scenes. Waltham, MA: Academic Press.

Karagiozis, M. F., & Sgaglio, R. (2005). Forensic investigation handbook: An introduction to the collection, preservation, analysis, and presentation of evidence. Springfield, Ill: Charles C Thomas.

Mozayani, A., & Noziglia, C. (2011). The forensic laboratory handbook: Procedures and practice. New York, N.Y: Humana Press.

Pyrek, K. (2007). Forensic science under siege: The challenges of forensic laboratories and the medico-legal death investigation system. Amsterdam: Elsevier / Academic Press.

Sherris, D. A., Larrabee, W. F., & Larrabee, W. F. (2010). Principles of facial reconstruction: A subunit approach to cutaneous repair. New York: Thieme.

 

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