Fighting Crime With DNA

Author: Hanah Gomberg

Editors: Galiba Anjum and Cynthia Zhang

Artist: Nicole Wang

Although corrupt, law enforcement and the justice system today play a crucial role in our current lives. One of the most common pieces of evidence used by forensics scientists to identify suspects is DNA. Since law enforcement is vital, it is essential to know which components help police and lawyers determine who may have committed a particular crime. DNA and biological evidence help convict rapists, robbers, and murderers, ultimately providing citizens a safer place to live. Some common questions surrounding this topic are: what are biological evidence and DNA testing? How do forensic scientists collect it, and how do they use it to solve crimes? Why is it relevant to the world we live in today? Although the answers are nowhere near as simple as to be answered in one sentence, this article will provide the information needed to answer these questions.

Every person is different when it comes to their biological makeup. All cells in the human body, except for red blood cells, have DNA sequencing. This sequence differs from person to person; no two people can ever have identical sequences. In forensics, biological evidence is anything that the perpetrator or victim leaves behind of their natural makeup. Usually, the first thing that comes to mind is fingerprints. Anyone who has ever watched crime shows or movies such as Criminal Minds would know its importance. Gathering fingerprints is commonly known as dusting. Since forensic scientists have spent many years perfecting the technique to collect them, they are the easiest crime scene evidence to trace back. They are created out of the sweat in your body and are often left behind if not intentionally destroyed, which is why it makes it relatively easy to acquire while making for very reliable evidence because all fingerprints are different. However, they are not the only type of biological evidence. Hairs, semen, and blood can all be checked through a DNA database to confirm or deny a suspect’s testimony.

When collecting biological samples, scientists consider various factors. For example, they have to make sure they are getting as many cells as possible in the sample. Scientists also must minimize degradation and ensure that there is no contaminated evidence. The best way to collect evidence is never to remove the stain, whether it be blood, semen, or a fingerprint, from the object since you are at risk of damaging the evidence. Ideally, the stains would be in a shiny non-porous surface that can move; however, that is usually not the case. People must cut off stains on the wall or any immovable surface. Yet, they have to be extremely careful handling the evidence. For example, if people improperly bleach scissors or tweezers when handling evidence beforehand, it might contaminate the sample and make it harder to retrieve information from the DNA.

The drawbacks of biological evidence do not stem from its unreliability, but many outside factors such as human error, controversial issues surrounding investigations, and the ‘CSI effect.’ Thus, its reliability is compromised since it has come in contact with other biological material, and proper DNA profiling cannot be made. Additionally, DNA profiling is generally more useful when excluding suspects that are not guilty. Many controversial issues have been raised where biological evidence is concerned, such as DNA dragnets, which occur when the police ask for DNA evidence from people from a geographic area that may fit a description. A well-known example of this comes from a famous Louisiana lawsuit where they conducted a DNA dragnet, forcing 1200 men to partake in it to assist the police in locating a match to the genetic profile. While the investigation was not successful, the men’s profiles were still entered on the database even though they had not been previously accused of any crimes. Thus, this case raised many quandaries about ethical issues around taking DNA dragnets. Finally, the ‘CSI effect’ is the popularization of the often unrealistic notion that biological evidence is the only acceptable or reliable way to solve the crime. This phenomenon occurred through the popularization of forensics through TV shows like CSI.

Biological evidence is an extremely accurate way to prove the culprit and confirm or deny any testimonies and the person’s part in the case. The odds also work in favor of law enforcement as out of the thirteen markers, the chance that any two people have identical DNA and were both at the crime scene and left proof behind is one in ten billion. Since there are only about seven and a half billion people on the planet, the chances are null.

Additionally, the likelihood of two people selected randomly having identical DNA is 1 in 5 trillion; therefore, also void. Biological evidence can also be harvested from minute quantities that may seem invisible to the naked eye but will prove very useful in the laboratory. The only major component that could make the evidence go from probable to unreliable is mishandling and contaminating, however, the chances of that happening are extremely low as forensic scientists have developed many techniques to keep that from happening. Forensic scientists have gotten so good with creating DNA profiles that you no longer need blood or semen to complete one. Nowadays, scientists can simply use a few skin cells to generate profiles; therefore, it has become much easier to catch perpetrators. However, robbers have become much savvier when committing crimes. For example, they have started to wear gloves to keep from having their fingerprints identified and hair nets to prevent hair from falling off. Still, now with the new skin cell identification, it has become nearly impossible not to leave traceable DNA behind.

Overall forensic scientists are a fundamental part of the world we live in today. The development of biological evidence, DNA profiling, and fingerprint identification is crucial to not only scientific evolution but our safety. DNA sequencing is critical when proving the culprit, thus aiding scientists and the police when solving high profile crimes where there are many variables and witnesses involved. Despite that the methods of collecting biological evidence are overall very accurate, there are several ethical issues in gathering the evidence. Having many DNA profiles in the system may seem beneficial to the people involved; however, dragnets can be a violation of privacy and fundamental human rights.

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