The Use of Firearm Cartridges for Forensic Evidence - Essay Example

The Use of Firearm Cartridges for Forensic Evidence The Use of Firearms Cartridges for Forensic Evidence Introduction Forensic evidence is evidence that is used for legal purposes or in a court of law to solve crimes such as murder. The evidence is obtained scientifically using a crime laboratory. There are many types of forensic evidence used in solving crimes such as bullets, firearm cases, blood tests and DNA. Cartridges have been used as forensic evidence to identify which particular firearm was used to fire the bullet. The cartridge cases found at the scene are analysed and comparisons and matches made using computer technology. A lot of items and information is collected at a crime scene these are then examined and analysed in crime laboratory. A cartridge sometimes known as a round or shell is the covering around the bullet. These are analyzed in the laboratory and the results can be used to determine which firearm was used. This evidence is used legal proceedings to prosecute a crime case. Cartridge Analysis No two firearms can produce the same unique on fired bullets and cartridge cases. It is this fact that makes it possible to analyze cartridge cases found on a crime scene to determine which particular firearm was used to commit the crime. Due to the process of manufacturing and the use of the firearm, the characteristics on the surface of the gun cannot be similar to those found on another gun. Firearms do not change over time and that is why it is possible to still identify that a particular firearm was used in a crime even years after the crime has been committed. Most investigators will want to know whether a suspect firearm was used to fire bullets or cartridge cases found on a crime scene. The unique markings created on a cartridge case are identified by firing a gun and comparing the markings on a test fired cartridge case. It is the similarities in these markings that will prove that a specific gun was used in the crime that is being investigated. Computer technology has made it even easier to do the cartridge analysis. A database is created of marking images from various firearms. Specific markings are created by a gun when a cartridge case is test fired and these are then entered into the database. Comparisons and matches are made against the database and the firearm is then identified. The database can also be used to link two or more crimes such as in the case of a serial killer. The cartridge cases from each one of the crime scenes are analyzed and the results can determine whether the same gun was used in all crimes (Jackson & Jackson, 2011). Cartridge Case Markings The analysis of the cartridge case markings involves two stages. The first stage in firearm identification is to check for similar class characteristics. These are characteristics that are common to a particular group of items. The class characteristics for firearm and bullet identification are the riffling pattern and the caliber of the firearm contained in the barrel. Classes for cartridge case and firearm identification include; breech marks, firing pin impressions, extractor marks and ejector marks. During this stage if there any dissimilarities, there is no need for further analysis. Where similar characteristics exist then the analysis moves to the next stage. This stage deals with the individual characteristics. These characteristics are random imperfections that are unique to a particular firearm. The individual markings will be made due to the manufacturing process, use of the firearm or damages. The transfer of these individual characteristics from the firearm to the cartridge casings is what makes the identification of the particular firearm possible. The unique marks are introduced to the firearm once the gun is loaded and does not have to have been fired for the marks to exist and be identifiable. The uniqueness of the individual markings is due to the fact that the materials that the cartridge casings are made of are different from the materials used to make the firearm. Cartridge casing is made of metals such as brass, steel or plastic. It is therefore easy for the firearm to be marked once it is loaded. There are two types of individual markings; the striated action marks and impressed action marks. Striated marks are scratches and are formed due to lateral movement between the cartridge case and the inner surface of the firearm and appear like a scrape. Impressed action marks are due to the impact caused between the cartridge case and the firearm due to velocity and pressure and leave an indented marking. Comparisons are made using a microscope to get a match (Jackson & Jackson, 2011). Quality of Forensic Evidence The identification of cartridge markings is done using the application of forensic science and technology. One rarely questions science as results through science have been proved and tested. Questions however arise on what happens to the evidence from the time the cartridges are discovered at the scene and the time the lab technician starts carrying out tests on them. The lab reports given to investigators are normally not questioned. Forensic identification uses science which we all believe can be empirically tested and results are rarely wrong. When a DNA test is done under no circumstances can the results be questioned or doubted. The question will arise on the integrity of the results. Questions may be asked on how secure the cartridges were from the time they were discovered to the time the lab technician started the tests. The evidence goes through a process before it is actually tested and analysed and will pass many hands. It has to be transported from the scene, packaged, labeled, stored and moved to the lab. Anything could happen to the evidence even before the lab technician starts the analysis. The possibility of wrong labeling and mixing up with other evidence exists. There is also the issue of the integrity of the lab technician and the laboratory. Is the laboratory properly equipped to carry out the tests? Is the lab technician trained and qualified to carry out the tests? It is for this reason that standards have been made for both the laboratory and the lab technician. The laboratory must confirm to certain quality standards and have the necessary tools to perform the tests. The lab technicians must have the right and relevant education and experience to perform their duties. If there are no questions regarding the integrity of the lab and lab technician and the process then there is no reason to question the tests done using firearm cartridges to determine the firearms used in a crime. The validity and authenticity of the forensic tests should not be in question. Conclusion Forensic evidence can be used in a court of law to solve crime. Firearm cartridges collected from a crime scene can be used to identify the specific firearm that was used. The cartridges have specific markings which can be compared against a database of firearm markings. It is the uniqueness of the markings on the firearm cartridges that make it possible to identify the firearm. The laboratory should pass certain quality standards and the lab technicians need to be of high integrity with the requisite education and experience. The forensic investigator can be rest assured that the lab reports from a firearm cartridge case analysis are authentic and use it in legal proceedings to solve a crime (Jackson & Jackson, 2011). Reference Jackson, A. R., & Jackson, J. M., 2011. Forensic Science. Essex: Pearson Education Limited. Read More