Applying Biology to Identify and Analyze Samples from a Crime Scene - Essay Example

FORENSIC BIOLOGY Forensic Biology Name Grade Tutor Date Criminology as the study of all the aspects relating to crime has continued to advocate the inclusion of technologically dependant methods to analyze and investigate crime scenes. This is with the understanding that criminals are aware of continued innovation in technology and as such continue to work hard to conceal any evidence that would expose their identity or traits. Forensics is a practice of methodically building incriminating evidence based on traits found within a crime scene. There are diverse avenues of forensics which is generally an audit process meant to uncover clues that can conclusively identify a crime which may have been committed and if possible identify the people involved. Forensic biology involves applying biology to identify and analyze samples from a crime scene and eventually match these samples to people who were likely at the scene of the crime (Forensic biology 2011). Many investigations especially those involving crime that results in bodily harm will to a large extend rely on forensic biology. Finger prints, bodily fluids including blood are some of the samples of interest for investigation and analysis to ascertain the people involved in the crime. These samples are identified and collected from the scene of crime by a laboratory scientist for onward tests within a well equipped laboratory. However the equipment needed to analyze such samples remains expensive and this process may take varying periods of time depending on the test being performed. There also must be a broad coordination between the activities taking place within the laboratory confines and other investigations processes which may result in the arraigning of suspects in an identification parade and the extraction of body fluids like blood for onward analysis and matching. This can be a strong investigation breakthrough if the samples earlier extracted from the crime scene match those extracted from a suspect eventually brought in police custody. These samples can then be carefully prepared and delivered by the prosecution as evidence against the defendant in a court of law. The police force world over faces a number of pertinent issues when it comes to investigations for crimes committed and the evidence tied to these crimes. As criminals become more sophisticated in their quest to erase any traces of evidence that could implicate them, law enforcement officers, lawyers and courts are encountering an uphill task in proving the guilt. However the advent of technology has brought with it techniques that are now able to aid in investigations and enable the prosecution to establish a water tight case. It suffices to generally mention DNA typing and a few other techniques in aiding investigations. These techniques will mainly suffice for circumstantial and corroborating evidence in cases where identification evidence is inadequate to sustain a case against the defendant. The suitability of this approach in circumstantial evidence is so because this evidence focuses on proving a factual matter in relation to other events or circumstances from where the occurrence being investigated can be reasonably inferred. Similarly while considering the corroborating evidence we notice that this is normally different from but supplements and strengthens evidence already presented as proof lending to the suitability of using these techniques (Swanson, Chamelin, Terito and Taylor 2008). Aronson (1974) puts forth a scenario of a case in 1987 that was among the first to employ the use of DNA typing to sustain a prosecution against a serial rapist. It was however necessary for the prosecution to bring in expertise advice in order to convince the jury that the evidence derived from the DNA typing technique was credible enough to sustain the conviction of the defendant. This option was considered after it appeared inevitable that the prosecution could not sustain a case against Andrew the alleged rapist though other circumstantial evidence pointed to him being considered as the prime suspect. In reading further the story of DNA on trial however brings out a number of factors that can be challenged even when DNA typing is used as a technique in criminal investigations. Turvey (2009) explains a number of aspects that can be considered to establish corroborating evidence. Case linkage also called linkage analysis defines a process to determine whether or not there exists a hidden relationship between two or more previously disparate cases through some form of analysis of the crimes. Accordingly the criminal profiler may employ modus operandi (MO) because this technique can provide an array of information about the offender. Further still MO comprises learned behaviour that can evolve and develop over time making it an essential technique in criminal investigations. Becker (2008) explains the ideals in handling DNA evidence considering that this will eventually become one of the water tight methods that a prosecution can be sustained. In appreciating DNA typing and other forensic techniques as methods of criminal investigation it will be necessary to note that its suitability is based on a myriad of factors the most challenging of which is the expertise required to interpret and express the results as evidence (Findlay and Grix 2003; Cole 2001). It is most probable that techniques such as DNA typing as much as they are almost full proof in criminal investigations will take a little while to gain collective support from the legal fraternity. Generally as mentioned above the success of any investigation is related to a direct mapping between the samples from a suspect arraigned on an identification parade and the sample at the lab picked from the crime scene when the prosecution process eventually begins. Since rape is a bodily crime where the victim and defendant must have body contact a laboratory scientist called at a scene of an alleged rape to carry out forensic process will be interested in identifying anything within the crime scene that can be analyzed to provide conclusive evidence to assist in the identification and the possible prosecution of the persons involved. Fingerprints have been long known to provide one of the most concrete identity clues from a crime scene. This is based on the understanding that each person has a unique finger print pattern. Latent fingerprints being used as a method of a unique identification has a long history. The database that holds fingerprints has grown massively over time and an automated fingerprint identification system (AFIS) can be accessed to retrieve stored prints. However errors in the AFIS are rare but possible which may be through human intervention. However, fingerprint error in latent prints does occur especially due to the latent print examiner. The AFIS is also used to identify biometric fingerprint records related to a criminal history as well as identifying latent prints from a crime scene as is the case here. The AFIS as one of the suitable tools may be used to derive a list of all the offenders in the biometric fingerprint database following a search query. The latent print collected at the alleged rape scene can be subjected to this enquiry to try and identify the offender. Since latent fingerprints are present at this crime scene the laboratory scientist may use powders that stick to the moisture in the fingerprint and contrast with the background to make the prints more visible. After this development process the fingerprint can be recorded through photographing. Fingerprint identification may not be sufficient in its own capacity to establish a full proof identity of the offender. This must be combined with other analytical tests such as DNA sequencing to add weight to the identification (DNA Fingerprinting 2011). Arriving at the scene of the crime an investigator will asses a number of things at the scene. At a general level there may be obvious clues such as blood stains and other susceptible fluids. There will also be hidden clues such as fingerprints and colorless stains which could be on brightly colored garments. Since the case under study here is an alleged rape, bodily fluid clues will attract the most attention. During the collection of this evidence the investigator will be keen to identify all these categories of clues. Four sets of evidence for this study are under consideration by the laboratory scientist and include a window bearing latent fingerprints, a blood pattern on a wall, a wet stain on a white garment and a clump of white cotton fibres. The laboratory scientist has the blood pattern on the wall as another sample to consider at the crime scene. Several analysis tests relating to this blood pattern may be conducted by the scientist. Blood pattern analysis (BPA) is among the known forensic sciences. Technological advancement has modeled this process to higher levels with advanced analysis involving DNA which is possible and available for use by criminologists to identify offenders. While carrying out a BPA at the scene of the alleged rape, the scientist is going to consider the following factors: Movement of persons or objects during and after the blood shed The area of the impact’s origin A chronology of the events at the scene of crime Position of the person during the blood shed Armed with blood splatter analysis knowledge the scientist will correctly collect and preserve the blood from the pattern on the wall at the alleged rape scene. The next step involves categorization of the pattern which can either be passive, projected or contact stains. The stain or pattern will also be analyzed to ascertain if it was a velocity impact stain. At the alleged rape scene there is also a wet stain which is not visible yet on a white garment. It is important to realize at this point that DNA profiling remains an invaluable tool to solve crimes. The burden therefore remains with the laboratory scientist to accurately identify the stain at the crime scene. A presumptive colour test is mandatory in this case and especially because of the nature of the wet stain which is colourless on a white garment. This will be followed by a test that uses an antibody such as haemoglobin for blood or P30 or prostatic antigen for seminal fluid (Conti and Buel 2009). DNA quantification is currently adopting a molecular approach which makes use of three or four dye real time PCR instrument (Conti and Buel 2009). This can be implemented in most laboratories without the need to purchase any new equipment. The laboratory scientist will therefore quickly achieve a DNA profile from the wet stain that was at the crime. A suitable sample in this case maybe one that positively passes the seminal fluid tests. This being alleged rape; semen would be one of the likely fluids at the scene of the crime and thus a proof of its presence points towards a possible rape situation. The clump of white cotton fibres found at the scene can also be subjected to a variety of tests by the laboratory scientist. A forensic fibre investigation can be utilized at this point. The clump of cotton fibres at the alleged rape scene will be collected and matched with those collected from the victim to determine whether there is a connection. The lab scientist will therefore collect the fibres which can then be microscopically searched and matched based on colour and morphological characteristics. A microspectrophotometer will be used to carry out a colour analysis ((BBC: Crimewatch 2011; Cox 2011). It is generally important to consider that an analysis of the samples from a crime scene needs to be as conclusive as possible. This is necessary in order to help the court to arrive at a ruling that is just. Bloodstains are important as evidence in the forensic biology process. The stain or quantity of blood at the scene points to important clues on the nature of the crime. Blood spatter is vital in determining the weapon that may have been used to inflict injury. Blood also contains the genetic information of the person in their DNA. Therefore an individual’s DNA sequence can be readily derived using the polymerase chain reaction (PCR). Generally DNA can be examined from various human samples that include blood, seminal fluid, hair or saliva. Considering that the laboratory scientist is investigating an alleged rape, the blood pattern on the wall and the wet stain can be picked up based on a limited budget as vital analysis samples for onward submission to the court. DNA sequencing on both samples is likely to provide conclusive proof of the likely identity of the persons involved at the crime scene. Since DNA sequencing also tests for other human body fluids other than blood, the wet colourless stain on the white garment can be identified and proven to either be semen or not which could further strengthen the case. The latent fingerprint and the clump of cotton fibres as the other samples found at the crime scene may not be analyzed conclusively because an analysis may not provide a match even if the AFIS was used. Again if the alleged rape was carried out in a place publicly busy it may be near impossible to provide conclusive proof. Therefore faced with a limited budget, the laboratory scientist may consider analyzing the blood pattern on the wall and the wet stain on the white garment to build evidence to support a submission. Reference List Aronson, J.D 1974, Genetic witness: science law and controversy in the making of DNA Profiling. New Brunswick: Rutgers University Press. BBC Crimewatch: Forensic analysis of fibres. 2011. [Online]. Available at: [19th Aug 2011] Becker, R 2008, Criminal investigation 3rd ed. Sudbury: Jones & Bartlett. Cole, S.A 2001, Suspect identities: A history of fingerprinting and criminal identification. Cambridge: First Harvard University Press. Conti, T and Buel, E. 2009. Forensic stain identification by RT-PCR analysis. [Online]. Available at: [19th Aug 2011] Cox A. C. 2011. Forensic fiber analysis. [Online]. Available at: . [19th Aug 2011] DNA Fingerprinting: World of forensic science. 2011. [Online]. Available at: [19th Aug 2011] Fibre analysis. 2011. [Online]. Available at: [19th Aug 2011] Findlay, M., and Grix, J. 2003. Challenging forensic evidence? Observations on the use of DNA in certain criminal trials. Current Issues in Criminal Justice, 14(3), 269-282. Forensic biology 2011. [Online]. Available at: [19th Aug 2011] Turvey, B.E. 2009. Criminal profiling: An introduction to behavioural evidence analysis, San Diego: Academic Press. Swanson, C., Chamelin, N., Terito, L and Taylor, R. 2008, Criminal Investigation 10th ed. New York: Mc-Graw Hill. Read More