Evidence-Based Study “DNA Field Experiment

Evidence-Based Study “DNA Field Experiment”




The capacity of any government to provide security and protection for its citizens ranks highly in the ladder of priorities. In fact, governments utilize a large amount of their resources or GDP in safeguarding the security of the country both from within and without. However, the ability of any government to eliminate crime or at least reduce the rates of crime in any locality depends on its expediency in solving past acts of crimes. The identification and solving of criminals in the country goes a long way in sending a stern message to criminal gangs, as well as reducing the rates of crimes in localities. In the past, the identification of individuals who took part in criminal activities mainly revolved around dusting for fingerprints. Of course, it is well recognized that every person has unique and distinctive fingerprints that are not similar to any other person’s fingerprints (Ratcliffe, 2003). There are three categories of fingerprints that may be used in criminal investigations including visible, plastic and latent fingerprints. Visible fingerprints are images that are left behind in crime scenes in dirt, blood or other materials, where they can be seen by naked eye. Plastic fingerprints are molded on surfaces such as clay, wet soap or mud where their impression is retained. Latent fingerprints, on the other hand, are the most common types of fingerprints. These are essentially greasy imprints that are left behind by oil in or on hands and fingertips on hard surfaces (Ratcliffe, 2003). Of course, shiny surfaces offer the best and clearest impression of latent fingerprints. However, latent fingerprints may be lifted or their visibility increased in varied materials using different techniques. In most cases, the standard powder, which is an organic compound, is used as it adheres to the fingerprints’ oil thereby enhancing the visibility of fingerprints. A piece of heavy tape would then be pressed onto the visible prints and peeled back thereby lifting the print. In case of porous surfaces, fumes from ninhydrin or iodine are used in a special chamber to lift the fingerprints’ impression to the surface (Rand & Catalano, 2006). The clear prints thus obtained are passed to fingerprint specialists who compare the fingerprint impression patterns to possible suspects. Of course, the computerization of police departments and law enforcement agencies makes it easier for the agencies to identify and apprehend criminals. However, the use of fingerprints in the identification of criminals is based on the assumption that criminals leave their fingerprints at the scenes of crime (Rand & Catalano, 2006). This is not always the case as criminals, may wear gloves thereby ensuring that no fingerprints are left in the scenes of crime. This underlined the necessity of coming up with other techniques of identifying criminals, which gave rise to the use of DNA testing and analysis.


DNA (Deoxyribonucleic Acid) stores the human body’s genetic information or code. It is present in varied items emanating from the human body including hair, saliva and blood among other bodily fluids. An individual’s DNA, just like fingerprints, is unique to him or her and is used in the identification of the genetic characteristics of an individual (Butler, 2005). This underlines its importance or vital nature in the identification, arrest, as well as subsequent prosecution of suspects in a crime. Traditionally, DNA has primarily been used in investigating and identifying criminals involved in violent crimes. However, its use has been extended to solving property crimes involving burglaries.

The processing of DNA is usually a painstakingly lengthy and costly affair. Biological evidence is usually obtained from victims, scenes of crimes, suspects or even their belongings. In burglaries or other crimes, perpetrators leave behind varied biological materials that can be used in identifying, apprehending and prosecuting them (Butler, 2005). These include saliva, skin cells and blood. It is, therefore, imperative that biological evidence in crime scenes is carefully collected and stored, as well as submitted to the crime lab so as to ensure the analysis of the sample for use in investigations. On the same note, evidence has to be properly handled so as to avert the possibility of contamination or decomposition (Rand & Catalano, 2006). This is especially considering that the potential for analysis of biological specimen may be jeopardized by improper handling.

In the creation of DNA profiles, experts enter the biological material to computerized databases where the samples are matched against those of specific suspects. It is worth noting that DNA profiles obtained from crimes may be searched against the DNA profiles of convicted offenders. On the same note, DNA profiles pertaining to different crimes may be compared against each other so as t allow for investigation of linked cases (Rand & Catalano, 2006).

The identification of suspects is carried out using the Combined DNA Index System (CODIS) system, which is a computer system that incorporates the DNA profiles that are created by state, Federal, as well as local crime labs in the US. This system incorporates three hierarchical components. At the top is the National DNA Index System (NDIS), which is under the Federal Bureau of Investigation (FBI). Other hierarchies are the State DNA Index Systems (SDIS) and the Local DNA Index System (LDIS), both of which are under the states. Enormous amounts of forensic information is held by the databases including offender profiles, information pertaining to unidentified human remains, as well as other forensic information obtained in crime scenes. These databases allow for the identification of suspects after the collected evidence is entered in the database and matched up to the information or profiles in the databases. Specific techniques for collection of evidence are used in the collection of biological evidence in burglary crime scenes including items touched, revealing the motives, examining points of entry, as well as retracing the steps of the burglars. The evidence thus collected undergoes a complicated and lengthy analysis process involving varied stages such as preliminary testing, DNA profile generation, CODIS entry, and case verification or confirmation of sample in varied databases. After this, the matched-up evidence is submitted to police departments for location and arrest of suspects, alongside other post-arrest procedures pertaining to processing f confirmation samples from the suspects.


The application of DNA testing has been considerably suppressed in most cases. This suppression has been mainly based on the notion that the use of DNA testing is cost prohibitive. In determining the efficiency and effectiveness of DNA testing in solving crimes and lowering criminal rates, it is imperative that one examines the outcomes, as well as implications pertaining to the cost of solving these crimes relative to the overall cost of DNA testing. Of course, DNA testing is recognized as considerably complicated or complex, as well as relatively costly. While this may be the case, its efficiency in solving crimes, as well as cost effectiveness is undisputed.

The effectiveness of DNA Testing was definitively proven in a research study dubbed “The DNA Field Experiment”. This study, carried out between November 2005 and July 2007 aimed at examining DNA forensics’ effectiveness in investigating property crimes. The research was carried out in five communities including California’s Orange County, Denver, Topeka, Los Angeles and Phoenix. A total of 500 crime scenes were used as sources of biological evidence. A half of every area’s cases was assigned to a control group by the project protocol, while the other cases had their biological material subjected to DNA testing. A large number of the crime scenes that were used as samples were residential burglaries, while the rest were commercial burglaries, as well as automobile thefts. This research aimed at examining not only the effectiveness of DNA testing on investigations, but also its impact on the rates of suspect identification, arrest, as well as conviction. This information was compared to cases that did not involve DNA evidence. Considering the cost and complication of DNA processing, the research aimed at investigating whether the outcomes produced by the use of DNA evidence justified the costs associated with DNA Testing.

First, the outcome of the research revealed that the use of deoxyribonucleic acid evidence resulted in an increase in the rate of identification of suspects of crime. According to Roman et al (2008), the use of DNA evidence doubled the number of suspects identified. Across the entire research area, the rate at which suspects were identified was identified at 31% (Roman et al 2008). The difference between this rate and the rate at the control is significant as the later stood at 12%. In Denver, Colorado, the use of DNA evidence allowed for the identification of 56% of cases, a significant amount considering that the control group had an 18% rate of identification. Similar results were registered in the case of Los Angeles which had 41% identification rate compared to the 22% registered in the case of control groups. Orange County, Phoenix, and Topeka registered 19% against 11%, 16% against 4% and 24% against 8%, with all differences being found as statistically significant (Roman et al 2008). The statistical significance of the differences between the percentage of identification with the use of DNA testing and those that did not use DNA underlines the effectiveness of DNA testing in enhancing the process of identification in the case of burglaries.

In addition, the use of DNA testing and analysis is seen as increasing the rate at which criminals or suspects were arrested. On the overall, the use of DNA evidence resulted in an arrest rate of 16%, which was statistically different from the 8% arrest rate registered in the control group. A total of 173 arrests were made in the cases that involved the use of DNA evidence, while the control group registered a total of 86 arrests. The percentages were statistically different across all the states examined (Roman et al 2008). Denver, Los Angeles, Orange County, Phoenix and Topeka registered 29% against 14%, 29% against 14%, 10% against 8%, 3% against 0%, and 6% against 2% respectively.

On the same note, the evidence-based use of DNA evidence in investigation resulted in an increase in the cases that were accepted for prosecution. Law enforcement and reduction of crime would be impossible without apprehension and prosecution of suspects. The research outcomes indicated that the use of DNA evidence resulted in 19% prosecution rate on the overall, which was statistically different from the 8% prosecution rate registered in the control group that did not use DNA evidence (Roman et al 2008). This statistical difference was registered in four of the states with Denver registering the highest difference (46% against 17%), while Topeka registered the smallest difference (7% against 2%). However, there was no difference in the percentage of prosecution for Orange County between the cases using DNA evidence and those that did not as they both registered a 9% rate of acceptance for prosecution (Roman et al 2008).

Overall, the use of DNA was seen as five times more effective in enhancing suspect identification compared to fingerprints. The research, which examined varied outcomes, noted that suspects identified using DNA evidence had a minimum of twice the number of prior felony arrests, as well as convictions as the ones identified using traditional investigations. However, the effectiveness of the DNA evidence is dependent on proper handling of biological materials, which is why it is preferable that forensic experts handle them than patrol officers.

Of prime importance was determining whether the cost involved in the use of DNA evidence is justified by the outcomes. While it is well acknowledged that DNA is extremely expensive, the end result justifies the cost. Research shows that there are varied costs that are associated with the process of collecting DNA evidence. While evaluating the cost effectiveness, Roman et al (2008), found that the use of DNA inn processing one case involved an additional $1400 in costs, as well as $4502 for additional suspects that traditional methods would not have identified and a further $14,169 for additional arrests. The costs, however, represented the additional costs pertaining to identification, arrest, as well as subsequent prosecution of burglars who would otherwise have remained uncaught. However, the training of experts and law enforcement agencies would go a long way in reducing these costs. Nevertheless, the results challenge the notion that the collection and analysis of DNA evidence is cost prohibitive. This is especially considering the increased identification, arrest and prosecution of criminals. Scholars note that the safer communities resulting from brining violent offenders to justice, alongside the increased capacity for prevention of future violent and property crimes justify the cost of using evidence-based DNA in combating crimes.

Needless to say, the incorporation of the evidence-based DNA analysis in combating burglary would enhance the safety of the country and reduce crime levels especially with regard to burglary, violent crimes, as well as property crimes. However, their capacity to effectively combat crime is pegged on the legislation and policies guiding their operations. As noted, the costs pertaining to the usage of DNA can be lowered through increased expertise. This is complemented by the fact that the handling of DNA evidence by forensic experts rather than patrol police increases the likelihood that such evidence will be useful in the identification, arrest, as well as prosecution of offenders, be they first-timers or repeat offenders (Swanson, 2002). This underlines the importance of creating, as well as implementing laws and policies that enhance its utilization and efficiency in combating varied forms of crime. This is especially considering the potential savings in the costs that come with resolving crimes that would have otherwise remained unresolved (Swanson, 2002). Such policies would allow for increased training of officers so as to enhance the effectiveness of using DNA evidence in fighting crime.

In conclusion, security is one of the most fundamental components in any country. It, in fact, makes up one of the largest expenses for countries as they try to safeguard their security both from within and without. However, enhancing safety mostly involves solving present and past crimes so as to prevent future crimes. In the past, fingerprints were used in identifying culprits of crimes. While this method was largely effective, it failed in some aspects, which led to the usage of DNA in solving crimes. While there may be disagreements as to the effectiveness and cost effectiveness of using DNA in solving crimes, research shows that the usage would result in reduced crimes and enhance safety in the neighborhoods. This is through increasing the rate at which arrests are made, as seen in the research. In addition, they increase the rate at which culprits of crimes are apprehended, as well as the rates at which their cases reach the prosecution stage. This underlines the importance of incorporating these EBPs in fighting crime. As much as they may come with additional costs in regard to fighting crime, their outcomes or advantages offset these additional costs especially with regard to increasing safety and preventing future crimes. However, it is imperative that policies are made establishing and outlining the guidelines that will enhance the effectiveness of the use of DNA in combating crime. Such policies would allow for training and expertise that would allow for proper handling of DNA evidence and increase its effectiveness in safeguarding security.


Butler, J. (2005). Forensic DNA Typing: Biology, Technology, and Genetics of STR Markers. Academic Press

Rand, M., & Catalano, S (2006). Criminal Victimization, 2006, Bureau of Justice Statistics Bulletin, Washington, DC

Ratcliffe, J. (2003). Intelligence-led policing. Trends and Issues in Crime and Criminal Justice, no. 248, Australian Institute of Criminology, Canberra.

Roman, J.K., Reid, S., Reid, J., Chalfin., A., Adams, W & Knight, C (2008). The DNA Field Experiment: Cost-Effectiveness Analysis of the Use of DNA in the Investigation of High-Volume Crimes. Washington, DC: Justice Policy Center

Swanson, C. R., Chamelin, N. C. & Territo, L. (2002). Criminal Investigation. Boston: McGraw Hill.

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