My Essay Titled Improvements on Crime Scene Investigation

Improvements on Crime Scene Investigation
Jesse W Ratliff Jr.
April 15th, 2012
Dr. Deana Plaskon

Improvements on Crime Scene Investigation
According to the Federal Bureau of Investigation (2011), statistics of violent crimes in the United States went down approximately six and one half percent from 2010 to 2011. Their report also concluded that the decline may have been a direct correlation to the number of criminals behind bars who could not commit repeat offenses (para 1). It is the duty of law enforcement agencies to solve crimes and arrest offenders. It is the crime scene investigator who is tasked with locating, collecting, and analyzing evidence to present to the court system to prove the correct person(s) are charged with those crimes (Bureau of Labor Statistics, 2012). Crime scene investigation has improved over the years because of DNA analysis, digital photography, and regulations which monitor evidence collection and processing giving the investigators the advantage in solving crimes.
In order to understand crime scene investigation, one needs to understand the meaning of key terms used in the field. DNA Initiative (n.d.) defines DNA (deoxyribonucleic acid) analysis as the testing to identify the genetic material present in the nucleus of cells which is inherited equally from each biological parent. Chain of custody is defined by McGraw-Hill (2002) as “The witnessed, unbroken, written chronological record of everyone who had an item of evidence and when each person had it; also accounts for any changes in the evidence.” Sample comparisons are either of known or unknown sources. Unknown samples are those which are a) collected from crime scenes, b) questioned evidence which may have transferred to an offender, or c) collected from multiple crime scenes and are used to associate those crime scenes to each other or to a single offender (National Institute of Justice, 2010). The NIJ defines known samples as reference samples used to compare with evidentiary samples, elimination samples used to rule out persons involved or persons of interest.
According to the DNA Initiative, DNA fingerprinting, or typing/profiling as it is known, was first described in 1985 by an English geneticist named Dr. Alec Jeffreys. Jeffreys found that certain regions of DNA contained DNA sequences that were repeated again next to each other. Jeffreys also discovered that the number of repeated sections present in a sample could differ from individual to individual. By developing a technique to examine the length variation of these DNA repeat sequences, he created the ability to perform human identity tests.
DNA analysis has been utilized for the past 27 years at the time of this paper. Before this process came to be, identification of an offender or suspect would rely on fingerprint identification and eye-witness accounts (DNA Iniative, n.d.). Since the fingerprint database was not well-developed or easily referenced in its early stages, it was not always timely in assisting investigators. Often the samples were tainted by the time it was put to task in a court of law, making the defense’s argument easy if fingerprints were the only solid evidence against the accused. Since the courts’ acceptance (Andrews v. State of Florida, 1988) of DNA evidence in criminal trials in the United States in November 1987, DNA evidence has been used to prove innocence of many wrongly accused and imprisoned. The admissibility of the DNA evidence was upheld by the intermediate appeals court, which cited the testimony of the State’s expert witnesses. The use of DNA analysis has been a major investigative tool used by criminal investigators since it was introduced (PBS, 1996).
DNA can be collected in numerous methods. Any bodily fluid has potential for providing an sample of DNA. Blood, saliva, and semen are the common bodily fluids for DNA sample collection. Feces and vomit are also subject to testing for DNA; however, not all laboratories are willing to analyze feces and vomit, especially if other sources are available (the DNA Initiative, n.d.). Hair, skin, and teeth, or other bone material, as well as fingernails and toenails contain DNA and these sources can be used to when necessary, or when no bodily fluids are available. DNA samples, whether collected in a controlled environment for known sample uses or found at a crime scene must be secured and follow a chain of custody. According to the DNA Initiative, this process protects the integrity of the evidence and, therefore protects the reliability and credibility of the results of the sample comparisons.
The national database used for DNA sample referencing known as NDIS (National DNA Index System) uses CODIS, which stands for Combined DNA Index System, for the purpose of allowing local, state, and federal agencies to access and compare DNA samples (FBI, n.d.). CODIS is a combination of two indices: 1) the convicted offender index and 2) the forensic index. The CODIS software compares the Short Tandem Repeat values from the forensic index to those found in the convicted offender index and vice versa. The CODIS software and all training on its use is strictly monitored and regulated by the FBI (DNA Initiative, n.d.).
The ability to take photographs of a crime scene has been a key function of the crime scene investigation since the camera was invented. It is important to have a record of the crime scene even after the scene was cleared and cleaned. According to the Technical Working Group on Crime Scene Investigation (2000), Photography allows investigators, whether initially present at the crime scene or not, to inspect, theorize, and recreate the crime scene to reevaluate what may have taken place.
Digital technology brought forth the ability to take a photo, put it on a computer screen, and analyze with advanced features such as zoom, precise measurements, and share the photo with other agencies instantly over the Internet. Digital imaging also permits multiple images to be compiled and create panoramic or three-dimensional crime scenes to be further analyzed or used in recreation of the scene of the crime.
The United States Department of Homeland Security (2012) has established training facilities which provide law enforcement agencies and their officers and investigators to receive proper education and training in the field of photography. This training ensures the law enforcement personnel know and understand the proper methods and techniques for taking quality photos and avoiding mishaps in photography. Topics in the photography courses at the training facility include aperture, lighting, flash photography, and crime scene photography. Digital photography analysis and surveillance photography are very important to the law enforcement agencies providing crime scene investigative services, and the federal training centers are dedicated to proper instruction for the continued development and professionalism of photography in the field. The students of the training center will gain knowledge of how to properly enhance digital photographs using software such as Adobe Photoshop. The facility trains the student in the processes involved in making a photograph presentable to a court of law as evidence (USDHS, 2012).
Crime scene investigation is an important aspect of the criminal justice system. According to the United States Department of Justice (1999), the Department of Justice was established in 1870 to regulate the process by which crime scenes are investigated. In 1969, the National Institute of Justice was founded by the justice department as a research and policy agency. The United States Attorney General is the overseer of the justice department and the NIJ, as well as their policies. The Technical Working Group on Crime Scene Investigation writes procedural recommendations and guides to local, state, and federal investigative agencies, which are approved by the U.S. Department of Justice before the guides become law enforcement policy. Specific guides written by the TWGCSI may be viewed or downloaded at
The United States Department of Justice has created agencies to research, develop, and regulate the processes of crime scene investigation. Through education and training, law enforcement agencies and their personnel are constantly furthering their knowledge and abilities to perform tasks more effectively, and learn new techniques for fighting crime. By continuing development and refinement of processes used to collect, secure, and analyze evidence, such as DNA and photographs, the law enforcement agencies have the training, equipment, and resources to make it difficult for criminals to go unpunished for their crimes.


Andrews v. State of Florida. (1988). District Court of Appeal of Florida, Fifth District,
533, Southern Series, 2d, pp. 841.
Bureau of Labor Statistics. (2012). Occupational Outlook Handbook, (13 Edition). Police and Detectives, retrieved from
Federal Bureau of Investigation. (2011). Preliminary Semiannual Uniform Crime Report, January-June, 2011. Retrieved from
McGraw-Hill. (2002) Online Learning Center. Retrieved from
National Institute of Justice. (2010, August). Retrieved from
PBS. (1996). The DNA revolution: The DNA wars are over. Retrieved from:
Technical Working Group on Crime Scene Investigation. (2000). Crime scene investigation: A guide for law enforcement. Retrieved from
The DNA initiative. (n.d.). Retrieved from
The United States Department of Justice. (1999). Retrieved from
References (continued)
United States Department of Homeland Security. (2012). Digital Photography for Law Enforcement – Federal Law Enforcement Training Center. Retrieved from

Updated: April 16, 2012 — 1:00 am

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