Crime Scene Contamination: Implications for DNA Evidence - Research Paper

Introduction

Crime scene contamination is a serious problem that can jeopardize or stall a criminal case to last for years, render it difficult to solve or make the case unsolvable at all. In some cases, it can lead to the conviction of an innocent person, especially when the DNA of that person is accidentally transferred to the crime scene (Beitsch, 2017). Countless cases have been documented in which DNA evidence has implicated and exonerated many people of crimes they never committed (Hill and Trummel, 2005). In this case, it makes it a daunting task for the defense and the prosecution attorneys to comprehensively scrutinize the available evidence to ascertain its integrity for the case at hand. This kind of contamination can be described as the introduction of elements that were originally absent in the scene to make it impure or tainted. The contamination can occur at various stages, starting from the collection, packaging, transportation, storage, or analysis stage in the forensic laboratories. The principles of crime scene management clearly outline the procedures of securing a crimes scene to ensure that evidence is well kept, collected, stored, and transported to the lab with minimal or no contamination at all. Forensic scientists are aware of the sensitivity that lies with the integrity of evidence collected and thus have developed protocols that aid in the identification and reduction of contamination risks (Hill and Trummel, 2005). However, law enforcement has been apathetic and laggard in adopting and applying such steps to prevent or minimize contamination. The great significance lies in the need and efforts to minimize or avert crime scene pollution to maintain the authenticity of criminal investigations or cases. This paper explores various aspects of crime scene contamination, stages, means of prevention, and related importance.

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Aspects of Crime Scene Contamination

Preservation of the crime scene is one of the core aspects of crime scene investigation (Baldwin, 2017). The personnel involved in an investigation must ensure that the area is well kept without introducing new elements or moving out of the area with new elements be it chemical or physical evidence. The main agents of crime scene contamination are those who move in and out of the scene. These include the investigators, the police, the medics, the forensic teams, and many others. The greater the number of people that have access to the scene, the higher the chances of contamination of the scene or the available evidence. Generally, the person who accesses the scene of the crime can deposit fibers, hair strands, or trace material from their cloths. Also, they can potentially destroy fingerprints or latent or mix them up (Hill and Trummel, 2005). New footwear patterns can be introduced by the crime scene personnel as well as anyone who gets into the crime area. The logic lies in the fact that whenever two objects have contact with each other, traces of evidence are exchanged in the process. This means that every time there is entry and exit of a crime scene, traces of evidence are left behind, and while others are taken away (Baldwin, 2017).

Baldwin (2017) asserts that issues of great concern that need protection include trace evidence, biological evidence, clothing, and injury evidence. Trace evidence includes but not limited to dirt, adhesives, and tapes, twigs, leaves, bullet fragments, grass, gravel, and fiber. Biological evidence includes semen, saliva, urine, blood, skin, swabs collected from various parts of the body, and hair. Clothing evidence includes what is worn by the victim(s) and suspect(s) as they often contain biological or physical evidence that needs preservation from contamination, degradation or mix-up (Baldwin, 2017). Bodily injuries ought to be thoroughly examined by the forensic examiners, critically identifying the injuries and possible causes before recording and keeping the labels well and separately without confusion.

The first precautionary step that should be monitored is the number of people who have access to the area in which a crime has occurred. During this assessment period, the groups of investigators have to be conscious of contamination risks by establishing certain integral factors. Actions of the first responder should be scrutinized for they might have introduced traces of new materials to the crime scene (Baldwin, 2017). It should be ascertained whether or not there were any possibilities of transfer or movement between the victim(s) and suspect(s) or removal of crime scene items since the crime occurred. Traces of DNA can be transferred through tools to another crime scene. Tweezers and fingerprint brushes can potentially retain DNA from one surface to another (Beitsch, 2017). The investigative team should ensure that items recovered are well handled from the collection, packaging, and labeling, including the individuals who handled them and at what specific periods. Also important to be noted is the possibility of the secondary transfer taking place between the victims, suspects, or scenes.

Forensic Science and DNA Analysis

Forensic science has become a crucial tool in the analysis of DNA material in every investigative effort. It has increased confidence in the analysis f biological fluids as well as cells available at the crime scene (Fonnelop, Johannessen, Egeland and Gill, 2016). This technology has made it possible to easily associate a suspect with a crime through the analysis and matching of DNA samples found in the crime scene with that of the suspect. DNA technology is applied in all crime labs in the world in the analysis of DNA samples. Its efficiency cannot be understated because it has made it possible to xerox even negligible amounts of DNA and make it large enough to analyze and draw conclusions (Baldwin, 2017). This ability to copy even the smallest amounts of DNA derived from biological evidence has made it more critical for the crimes scenes to be protected from any kind of contamination because stained or touched surfaces can pick DNA traces from other entrants of the crime scene irrespective of whether they committed the crime or not (Wyatt, 2013). For this reason, everyone involved in the investigative process has to restrict themselves from spitting, coughing, sweating, or leaving strands of hair in the crime scene. This can not only cost valuable time but also provide a route out for a possible suspect, cloud surety of compromise how physical evidence is interpreted (Beitsch, 2017).

Levels of Contamination

Contamination levels are dependent on the size of the crime scene or the type of crime committed. The size will determine the possible number of personnel who will have access to the scene. For instance, a murder scene is often larger than a burglary scene, and the former often requires more people than the latter to be involved in the investigative process. In detail, the murder scene is always visited by first responder, medical examiners, investigators, paramedics, coroners, prosecuting attorneys, as well as supervisors (Wyatt, 2013). Also present might be family members, friend, and relatives. This increases the number of entrants into the scene, thereby jeopardizing the purity of evidence found at the scene. The investigative personnel should be knowledgeable enough to preserve the crime scene and restrict access and activities of the entrants to limit contamination of the crime scene.

Environmental Factors in Crimes Scene Contamination

While human factors are the major sources of crime scene contamination, environmental conditions also play a role in soiling a crime scene and interfering with evidence. Rainy weather can wipe away crucial pieces of evidence, including bodily fluids like blood, and diluting chemical evidence. It can also wipe or degrade traces of fingerprints or footwear evidence while also washing away stains before they are collected as pieces of evidence or documented photographically. Exposure to extreme sunlight or humid conditions can either dry fluids or interfere with their concentration making collection difficult (Wyatt, 2013).

In some instances, bodily fluids can be contaminated by bacteria or microbes while in other conditions, they can decompose to in a manner that can render the analysis difficult or inconclusive. Temperature changes and wind can interfere with evidence in a crime area. While extreme temperature conditions can potentially dry fluids, winds can blow away certain elements like dirt, sand, gravel, or carry away light materials that can be considered as evidence (Baldwin, 2017). Often, some pieces of evidence are labeled as frozen or cooked due to these weather conditions, especially the unsecured outdoor scenes. Indoors scene without cooling or heating capabilities can also alter the nature of the evidence that can be collected.

Securing Crime Scenes

A pre-secured scene has fewer risks of contamination because the scene becomes a no-go zone for unauthorized individuals who can interfere with the evidence. On the other hand, depending on the location of the scene, it can still be daunting to secure a crime spot. This is because of the events that might have happened before the scene was protected, including those who might have accessed the space before its preservation. In some areas, there are situations in which individuals enter the crime scene and leave unrecorded such as private residences, hotels, or homes. In such scenarios, the victim's family members are in a position to enter and exit the crime scene before the investigators arrive.

On the other hand, in cases like banks, if a robbery incident occurs, there is likely to be numerous traces of physical evidence left on the surfaces due to a large number of people entering the bank. If it is public space like a park, then the rate of contamination or interference with evidence is even higher because of the unregulated number of people that visits the public places (Baldwin, 2017). This extended rate of destruction of evidence presents an impetus challenge to law enforcement in their efforts to find out the truth about a case.

Even with less potential for contamination, post-secured crime scenes can still be contaminated if there are insufficient provisions laid down, allowing other entrants into the crime areas. Some complicated cases involve bureaucratic procedures in which additional personnel can enter the crime scene. Depending on the incident and who is involved, it can be challenging if no proper protocols are put in place beforehand to protect the scene of the crime. Certain scenes like residential burglary scenes can be less complex as compared to public areas. Less complex scenes are easier to secure with less personnel as compared to public areas, which require a huge number of crime-personnel to fully preserve from unauthorized entry (Fonnelop et al., 2016).

Challenges of Crime Scene Protection

Challenges of protecting a crime scene are numerous and are responsible for the inaccuracies recorded while dealing with contaminated evidence. One of such shortcomings is the full determination of the overall dimension or size of the crime scene. Some areas of crime are scattered, meaning the crime did not take place in one location. It is highly possible that the investigative team, especially from the first respondent, misses the scope of the whole scene and securing just a portion of it. The section left out might carry the real evidence that can easily crack a case. When trampled upon by other people, the areas outside the perimeter of crime can be contaminated, making it difficult to collect crucial evidence. The barrier tape used to secure a crime scene should not be the only barrier. Additional individuals might be needed to aid in the process unless the unit involved is understaffed while...