Crime Scene Investigation Case Study Essay

OBTAINING and RECORDING PHYSICAL EVIDENCEWhen it comes to identifying people that learn perpet pasture a criminal act, the most supreme means is through and through finger writes. When we atomic number 18 born, our fingermarks stay with us until we die and our bodies shekels decomposing. To the homosexual eye our reproduces tone of voice the same, however, further investigation will show that each of us spend a penny a unparalleled set of friction ridges that comprise our reproduces and sets our identity asunder from each other(a). At a ab manipulation snap, in that location atomic number 18 deuce different types of fingerprints that may be found. Patent prints atomic number 18 distinct to the human eye. Latent prints ar unintentional prints found on items of differentiate or at a crime scene (Un cognize, Obtaining and Recording Physical Evidence, n.d.).The powerfulness to stick out prints depends on the physical condition of the person who left the print, th e raise on which they left it, and the reflection of the glister which is employd to help visualize the print. Other circumstances that effect the visibility of potential prints is time and mental picture to elements corresponding heat and cold. However, in any case, prints should be attempted to be obtained. When latent prints ar smudged they lack the specific ridges to distinguish the print correctly. These types of prints may non be perfect for fingerprint analysis they may be utilized to provide other trace order.Before latent prints tramp be lifted and cultivateed they need to be discovered. Each print left in different types of surfaces have to be processed in a special way. The most common means is with the use of fingerprint demolishs or through chemic treatment. Most field turnouts supply a variety of colors so that the demolish clear contrast with the minimize on which they were left. The most widely employ colors argon scurrilous and whitebe f ar they are sales boothard colors that contrast on some objects.Fluorescent fingerprint powders help develop prints on multicolored surfaces, and anticipate the source of ultraviolet light. As with most equipment, safety goggles and gloves should be used to avoid un repayable exposure and harm to the investigator. It is important to have a delicate touch and a small amount of powder to make the latent print visible. Once the print has started to show up, continuing to brush with the direction of the friction ridges will make the fingerprint stand out. At that time, a photograph of the print should be taken and logged prior(prenominal) to lifting the print. If an investigator is in the field without proper powders, passing non-flammable evidence through the smoke of a burning piece of pine will cause soot to deposit on the object.Chemical processing of latent prints happens in the laboratory. Lab technicians are trained in using techniques that are indispensable by the federal law i n using many chemical mixtures to aid in processing evidence. Many permeable objects will drag the secretions from fingerprints and will not rub off as easy as they will on nonporous surfaces or objects. In order to draw off these prints visible, chemicals are utilize to react to the secretions to make the print visible. The amount of bear upon and pressure applied by the fingers will affect prints the most.Once the prints are visualized, and photographs have been taken, prints can be lifted and placed on a print card and transported to the lab for further processing. The most common method to use for lifting prints is rubber lifters and transparent lifting taping. Rubber lifters work the best on curved or un tied(p) surfaces, whereas transparent tape will lift the print in the position in which they were left on insipid surfaces.How to Lift FingerprintsThe basic police officers fingerprint kit should contain a fingerprint brush, blackness and bi-chromatic powder, lifting t ape, and fingerprint cards. There are several types of fingerprint brushes available, the one to use is a in-person preference. fibreglass fingerprint brushes have a better rate of to distribute the fingerprint powder evenly (Spraggs, 2007).Most crimescenes will utilize the black lifting powder however, the bi-chromatic powder will be actually helpful in processing prints on dark surfaces, because it is a mixture of the black powder with a white or silver powder. When the bi-chromatic powder is used on dark surfaces it will look light and it will show up dark on light surfaces.The best rule for processing latent prints using powder is to use less lifting powder than you think you are going to need. Many latent prints can be ruined by over processing with powder. David suggests give the print powder jar a quick shake before opening the lid then goes on to say remove the lid and place the fingerprint brush internal the lid (Spraggs, 2007). The lid will retain enough powder to start processing the latent print. A circumstantial amount of pressure applied while spinning the brush will produce a safe(p) print with good ridge detail. He mentions that excessively much powder will fill the ridges and over process the print and too minute will not produce enough, keeping in mind that too much contact amid the brush and the print will monetary value the print.Once the print has been developed it is time to begin lifting the print. Lifting tape comes in a variety of widths and compositions. General lifting tape is used on apartment surfaces and polyethylene tape is great for curved surfaces like door knobs. An important key in applying the tape is to keep it evenly and as glow as possible. David suggests using a credit card to ensure even and smooth applications. Securing the lifting tape about an inch from the edge of the print, then use the edge of the credit card to gently press the fingerprint lifting tape onto the surface (Spraggs, 2007). This process allo ws for thorough adhesion of the powder and the tape ensuring that commit bubbles are eliminated at the same time and being trapped in the tape. He in any case utilizes the credit card again when placing the tape to the fingerprint card.How Far Should Prints Be Trusted?Fingerprint analysis is not an look at science and has many potential flaws. One man was imprisoned for cardinal years in Massachusetts for shooting a police officer, only if to be released in 2004 when the fingerprint evidence that wasused to convict him was trumped by DNA. For a long time the Department of Justice contended that there was a zero error rate in fingerprint analysis. In a study conducted by FBIs Latent Fingerprint Section in Quantico, Virginia, concluded that the chance to be mistake a fingerprint for soulfulness else was 1 in 1097. This study was conducted on 50,000 pre-existing images and compared electronically against the on the whole data set, thus producing 2.5 billion comparisons.However, many advocates against the admissibility of fingerprinting pertain to skip on the bandwagon and believe the study does not reflect what happens in life. In life, partial prints from a crime scene can be untidy and send an invalid picture of the criminal. In an unpublished study conducted by 92 students that had one year of training where they had to concord archive and impostor crime scenes. The end result was 2 out of 5861 were incorrect, which produced an error rate of 0.0034% (Coghlan, 2005). Results from proficiency tests published and cited in the journal of Criminal Law and Criminology (Vol. 93, p. 985), base error rates occur at a 0.8% average, and have been inhabitn to be as high as 4.4%.Latent FingerprintsIn 1914, Dr. Edmond Locard establish the freshman rules on the minimum number of minutiae necessary for a positive identification. According to his study, if twelve or more concurring points are throw when the fingerprint is clear the identity is beyond debate ( Unknown, Latent Prints, n.d.). If there are eight to twelve concurring points are present the induction of the identity will be contingent on five extra points. They are the sharpness of the print, the rarity of its type, the presence of the center of the core and the delta in the exploitable part of the print, the presence of pores, and the perfect and obvious identity regarding the width of papillose ridges and valleys, the direction of the lines and the angular value of the bifurcations. If there were less than eight points present, the fingerprints could not provide a valid and accurate identity. Dr. Locard believed that approximately 40 pores in concurrence could establish individuality (Unknown, Latent Prints, n.d.).Fingerprint Detection veritable CapabilitiesCrime scene investigators use a variety of tools to help exculpate a case. Latent fingerprint espial and identification is among one of the greatest forensic techniques used. The value of fingerprint evidence is ins urmountable. An investigator needs to know how to detect, enhance and record the print that has been left behind not visible to the human eye. Latent prints left behind at the crime scene are the most common type of fingerprint evidence, but they are overly the ones that can cause the most problems, mainly because it is there, but not to the unaided eye. Utilizing optical, physical or chemical treatments to develop the print comes with precise judgment. The investigator or crime scene technician must distinguish between porous, non-porous and semi-porous surfaces water insoluble or water soluble, etc.Just like anything else, latent fingerprints will start to deteriorate and can lead to the want of clarity over a specific time because of numerous factors. Elements of this process include evaporation of volatile components (e.g. moisture), diffusion (e.g. through the substrate for porous surfaces and across the surface for non-porous surfaces), decomposition (e.g. bacterial action, oxidation, chemical breakdown due to heat and light, etc.) (Lennard, 2007). The rate of dehydration will depend on certain(a) factors like the temperature, humidity, and exposure to sun, air currents and the surface on which the print was left. mental picture to high humidity can result in diffusion of a water soluble print, causing the print to be lost, and any detection techniques to be ineffective.Using optical detection techniques will aid in alineing latent fingerprints. Luminescence will help display a weak friction ridge detail. The best optical detection is achieved by using short-wave ultraviolet (UV) light. This technique is highly effective because the light acts as a contrast between the surface by absorbing the light or reflecting it back showing the presence of print.Will DNA put back Fingerprints in the twenty-first Century?The use of fingerprints to help solve crimes was first-year suggested by Dr.Henry Faulds in 1880. Twelve years later, fingerprints that were left in blood at the scene of a double murder in Argentina were used to convict and identify the killer. However, the first fingerprints accepted in cost in the unify States didnt happen until 1911.When we are born, we have distinct patterns on the tips of our fingers that will only change under a biological variation, because once formed in womb, the ridges are permanent and unique to each individual. Biological variation is also known as the essential law of variation and is sometimes stated as Nature never repeats (Leo, 2005). There are three basic types of fingerprint patterns loops, whorls, and arches. Each of these patterns are arranged to give individuals unique ridges that make up the persons characteristics of fingerprints.It is when these ridges are examined under a microscope side by side with a known source that a person can be substantiate or eliminated as a suspect. With new technology, fingerprint evidence can be searched through automated fingerprint information systems (AFIS). Fingerprints are used to establish a persons identity in the United States and in every other country in the world. Fingerprints are not just used as evidence in a crime (criminal history), but for employment and security clearances.Deoxyribonucleic acid (DNA) was discovered in 1911. It was also discovered that this DNA was the carrier of genetic information. However, it wasnt until 1985 that the structure also established the uniqueness of each person. One year later, the first use of DNA in a criminal case was used to match a suspect to a double murder in England. The first case of DNA evidence admitted in a United States court didnt happen until 1988. Since then, over thirty-five states have admitted DNA evidence in one form or another while more than twenty-five states have the population frequency data or statistics to be admissible in court (Leo, 2005).DNA evidence is found at crime scenes as the presence of blood, semen, hair, skin, and saliva. In order to mak e a comparison a DNA profile must be extracted from the evidence and/or a sample taken from a known individual. A DNA profile is accomplished through a process called electrophoresis. subsequently the profile has been extracted, the results are recorded on an autorad and can be compared to other profiles. There are thirteen markers that are used to standardize a national data base called Combined DNA Index organization (CODIS) in the United States (Leo, 2005). To date, DNA is still emerging as we continue to move further into the technological future, and can be used for personal identification, employment, security clearance, or to track criminal histories.Every second of the mean solar day, millions of fingerprints are being searched via the automated fingerprint systems around the world. Thousands of crimes have been solved because of the fingerprint evidence left behind at the scene of the crime. In 1994, when CODIS began, there have been over 20,000 DNA matches. In Los Angeles County, California, more than 500 latent prints are matched to criminal offender on any given day (Leo, 2005). Both methods of identifying an individual play crucial roles in solving crime. Although fingerprints are still considered the golden standard for forensic evidence in the court of law (Leo, 2005), DNA is moving forward in being a very important tool to combat and solve crime. However, when it comes down to it, both techniques equilibrize each other and provide vital information to help find criminals.Works CitedCoghlan, A. &. (2005). How Far Should Prints be Trusted? New Scientist, 2517(187), 6-7. Retrieved January 21, 2013, from http//search.ebscohost.com.proxy.devry.edu/login.aspx?direct= unbent&db=a9h&an=18376323&site=ehost-live Lennard, C. (2007, December). Fingerprint Detection Current Capabilities. Australian Journal of Forensic Science, 39(2), 55-59. Retrieved January 21, 2013, from http//www.informaworld.com Leo, W. (2005, September/October). Will DNA Replace Fin gerprints in the 21st Century. The Print, 21(5), 1-5. Retrieved January 21, 2013, from http//www.fingerprintidentification.net/sitebuildercontent/sitebuilderfiles/dnavfingerprints.pdf Spraggs, D. (2007, February 01). How to Lift Fingerprints. Retrieved January 20, 2013, from Police Magazine www.policemag.com/channel/patrol/articles/2007/02/how-to-lift-fingerprints.as