DNA evidence is a technological innovation that has been developed and used to fight crime

 

 Abstract

            DNA evidence is considered as a significant crime investigative tool and technique. New technologies have been introduced to prevent crime, and improve the role of police but little is known about the DNA evidence, and its intended solutions. DNA testing using genetic materials allow crime investigators to match the suspect's DNA samples to samples at the crime scene. This paper aims to look at DNA evidence as technological advancement in criminal justice. The paper is structured into various sections which focus on the history of DNA evidence, DNA structures, Processes in forensic DNA samples, methods to analyze evidence, and interpret results, and the main basics needed in DNA evidence. Cities and towns that have adapted to this new scientific development have been listed. The conclusion shows that since the DNA evidence was adopted, it has made a significant contribution in criminal investigations. Additionally, the government should invest in technological advancements such as DNA evidence to improve efficiency and effectiveness.

 

 

 

Introduction

DNA technology has been adopted to control and prevent crime by police agencies.  DNA typing was discovered in 1986 by Alec Jeffreys who analyzed DNA samples in crime scenes and found matching DNA. DNA evidence is vital in the criminal justice system in that it does not only solve crimes but it also helps the police to ignore potential suspects and have a specificity, hence ensure fairness and accuracy. Police are also able to solve crimes through evidence found in the crime scene.  Besides, police can also compare crime scenes to DNA databases. In general, DNA technology has helped police solve cases. Today, DNA profiling is used in forensic science to conduct criminal investigations and secure convictions.  Until now, DNA evidence has made a significant contribution to the criminal justice system, and it is seen as new professionalism in policing as it has promoted accountability, commitment, and national coherence. The technology has enabled the police officers to develop evidence-based policies, promote special control, and improve the prevention of violations.  Since its discovery, forensic scientists and law enforcement have gained the ability to solve thousands of cases. Therefore, DNA evidence is a useful investigative tool that police agencies and law enforcement are using to collect evidence and to make decisions. While most cases needed proof back then, the DNA database, DNA in Forensic Science, and DNA Population Frequencies provides DNA evidence in most cases today.

The history of DNA evidence

Alec Jeffrey studied the genetic variation or in other words the genetic differences between individuals.  In his project, he compared humans with myoglobin gene and found that there were repetitive DNA or multiples copies of DNA between seals and humans (Tilstone et al. 2003). He concluded that the repeated sequences or in other words the repetitive DNA could differ between individuals. Dr. Jeffreys went further to examine the repeated sequences using a technique known as restriction fragment length polymorphism (RFLP). This technique focused on a restriction enzyme or a protein that is DNA cutting enzyme at specific recognition sites (Tilstone et al. 2003). The RFLP method was also introduced as a method for human identity testing where the DNA is extracted and restoration enzymes are used to cut the DNA or in other to divide the DNA into smaller segments.  Professor Jeffrey used the DNA segments and found that individuals have a different pattern and the different DNA patterns could be used as a problem-solving tool in criminal cases (Tilstone et al. 2003). Since 1995, crime scene investigators have been using DNA evidence to convict the guilty and to discharge the false accused individuals.

DNA structure

First, it is important to understand that all cells in living organisms contain DNA. Apart from the red blood cells, other cells contain nuclear DNA and during crime scene investigation, a nucleic acid is extracted. It is also important to note that a person has a distinct set of chromosomes and this means that even though a person inherits genetic materials from parents, he or she produces unique characteristics (Tilstone et al. 2003). Since DNA is made of nucleotides, Alec Jeffrey found that in the repeating units that form a DNA vary in each individual. Therefore, during DNA fingerprint, each individual has a unique fingerprint.  Focusing on the value of DNA evidence, it is important to note that people have different DNA and therefore it is easier to compare the DNA evidence from a crime scene to a suspect (Tilstone et al. 2003).  Another method of fighting crime is comparing DNA to known samples to identify the suspect. Also, the police can also identify a suspect by using linking a DNA profile with the Federal Bureau of Investigations. It is also advisable to use elimination samples to clarify the results. It is important to note that during DNA typing, each person has a unique DNA and therefore it is easier to identify a perpetrator.

 

DNA database

 Tilstone et al. (2003) add that DNA database also help in providing DNA evidence. For example, the FBI administers the Combined DNA Index System to all states and this is where they derive reference samples of persons accused of severe offenses such as homicide. Scientists compare the reference profiles to DNA results.  The FBI's nationwide DNA database contains the National DNA Index System and all states in The United States use the DNA Index System to search   DNA profiles.  Since the DNA Index System contains short tandem repeat profiles, U.S states can match the biological evidence, identity the perpetrators, and stop violent crimes.  The research suggested that DNA databases are more effective than forensic DNA typing in that the databases can locate suspects, and match offenders (Tilstone et al. 2003).  It is important to note that the national DNA database is found in local, state, and national levels.  These levels play a significant role in finding offenders since the investigators can address local cases, and forward them to state and national levels.  Another important thing to note is that laboratories are required to ensure quality assurance standards and conduct proficiency tests of analysts to ensure that the DNA profiles submitted into a DNA database are accurate (Tilstone et al. 2003).  Besides, all states that need their DNA profiles to be put into the DNA index system must sign a memorandum of understanding, which is an agreement between the DNA laboratories of a state and FBI'S Quality Assurance Standards.

 

 

DNA population frequencies

 In addition, DNA population frequencies are used to obtain DNA evidence. This is done when blood collected from a population is stored in a population database and the sample of a  specific number of people is counted and used to determine the genotype (Tilstone et al. 2003). Investigators also target a certain population and use the population data to calculate the frequency of concurrency. In some cases, the scientists may not know the ethnicity of the suspects and in such cases, scientists’ use a random match probability in ethnic groups and detect a random match probability (Tilstone et al. 2003). The scientists them compare a reference standard or sample to a sample of blood to find a DNA profile.  For example, population such as Caucasian Americans, and Southwestern Hispanics, generalization is made to construct databases.  An important point to note is that frequencies of DNA patterns of a population are estimated by counting occurrences in a population sample and determine if the occurrence is an upper confidence limit or lower confidence limit.

 

DNA in Forensic Science

DNA  in Forensic Science means that  scientists  conduct DNA analysis  or  they test  biological materials left  at the crime scene  to detect if the  biological materials  matches with the DNA of  a suspect (Tilstone et al. 2003).  Since it was developed, forensic DNA analysis has done a great role in solving civil and criminal cases. Note that each person has a unique sequences and the scientists only require to test 0.1% of   biological materials such as blood, skills cells, saliva, and other materials to confirm crime (Tilstone et al. 2003).  Forensic scientist uses a method known as DNA typing or detecting DNA types in biological materials.  The DNA typing reveals person-to-person variation and this helps the investigators to identify suspects. Scientists use different methods to show the differences. Research on DNA typing shows that forensic samples contain DNA which is then tested in the laboratories to produce absolute identification (Tilstone et al. 2003). The research paper also provides the methods and technology of DNA typing and DNA analysis.

 

 

 Processes in forensic DNA samples

 Biology

 The first step is biology and it means that in the crime scene, DNA is extracted from biological materials such as blood, semen, human tissue, and other materials (Tilstone et al. 2003). A process of DNA purification is done and STR region or DNA regions with repeated sequences are examined.

Technology

 The PCR technique is used to isolate the DNA cells and the copies produced are used to do STR analysis.  Sample genotyping is used to determine the repetitive DNA sequence.

 Genetics

  DNA profiling is done by using short tandem repeats (STR) and the forensic investigators compare the STR genotypes with suspects in the crime scene. If the investigators identify matches, the DNA profile and population database are compared to examine an identical STR profile (Tilstone et al. 2003). In general, it is important to understand that in order to find the DNA evidence, there must be a comparison between samples such as the comparison between crime scene evidence to multiple suspects or comparisons between DNA profile to a computer database.

 DNA evidence analysis 

 Various methods are used to establish identity in a sample of DNA. 

 Polymerase Chain Reaction (PCR)

 This is a copying process where many copies are generated. The process is important in that a DNA target sequence is generated and makes it easy to analyze forensic samples (Tilstone et al. 2003). Since most perpetrators do not produce enough evidence materials, PCR DNA is sensitive as it compares alleles to samples from biological materials.

 Short Tandem Repeat (STR) analysis

  STR analysis means that since people have a similar human genome and only 0.3% account for genetic variation, there are repeated DNA sequences or DNA regions that contain short tandem repeats (STRs) (Tilstone et al. 2003). These STRs are amplified by PCR and as a result, the STR show variations that make it easier to compare samples.

 Y-Chromosome analysis

 Y-chromosome marker plays a significant role in forensic investigations in that crime investigators can identity male perpetrators especially in sexual assault cases.

 Mitochondrial analysis

 In some cases, STR typing does not produce results and therefore mitochondrial DNA   helps recover the information. Mitochondrial DNA contains thousands of cells and this makes it possible to obtain a higher number (Tilstone et al. 2003). In other words, nuclear DNA produces only two copies while mtDNA produces higher numbers of mtDNA molecules.

After conducting DNA analysis, the DNA analysts give a laboratory report to police investigators and the prosecuting attorney to show DNA evidence.

 Basics of DNA evidence

 Gathering DNA evidence

The first important thing in the DNA evidence is to gather physical evidence and in this case, biological evidence is also physical evidence found at a crime scene if though it may not always be visible (Schmalleger, 2019). Biological evidence such as blood is collected and taken to the laboratory for testing.

 Identifying DNA evidence

Secondly, it is important to note that not all collected samples contain DNA information or in other words, some materials do not have enough cells for DNA testing. Therefore, it is important to collect common items of evidence such as facial tissues, eyeglasses, used cigarettes, pillow, blanket, fingernails, among other common item (Schmalleger, 2019).  It is also important to identify the possible location such as end, inside, surface area, scrapings, and more. Lastly, it is important to identify the biological source such as blood, sweat, mucus, saliva, semen, urine, and more.

 Crime scene integrity

  Another important step in DNA evidence is protecting the evidence. This is done by ensuring the maximum protection of the crime scene in order to achieve a successful solution.

 Contamination

 It is important to be aware of the risk of contamination and all law enforcement should ensure there are no incidental activities at the crime scene such as smoking, littering, among other actions that may cause contamination.

 Chain of custody

 Law enforcement should maintain the chain of custody by recording all scene notes including location, time, date, condition of the item, collection techniques, transportation, storage, packaging, individual handling the evidence, and more (Schmalleger, 2019). An important to note is that the chain of custody should be maintained since it is a legal document that will be needed in the trial. In case of any mishandling, the evidence will become questionable and it might not be used by the court.

 Transportation and storage

 The law enforcement officer should ensure proper handling of the DNA evidence. For example, blood stains should not be transported while wet but they should be dried to prevent mold growth. In general, most samples should be transported while dry and cold to prevent bacterial growth and base hydrolysis (Schmalleger, 2019). They should be transported overnight and they should be stored in a refrigerator. It is recommended that samples should be stored on bloodstain cards to enhance DNA longevity. The bloodstain cards should also be seals to ensure a full DNA profile. The benefit of proper storage is that the evidence can be stored for many years and it is used for post-conviction when there is no availability of DNA testing (Schmalleger, 2019). When all these steps are followed, the DNA evidence will be taken to the laboratory and the first thing that scientists do is to confirm if there are biological materials or what is known as the confirmatory test.

 How to interpret DNA test results

 Inclusion

 Inclusion results mean that there is a match where the DNA profiles of suspects and the DNA profile at the crime scene (Schmalleger, 2019). However, before arriving at the inclusion results, it is important to examine as many DNA locations as possible in order to achieve a powerful statistics.

 Exclusion

 Exclusion results mean that there is no match between the DNA profile of a suspect and the DNA profile at the crime scene. It is advisable to conduct other tests to confirm that the suspect is guilty.

  Inconclusive

 Inconclusive results mean that the DNA testing did not show any result to include or exclude the suspect (Schmalleger, 2019). This may occur due to insufficient DNA, a mixed sample that may result in more than one profile, among other causes that might hinder the collection of a specific type of evidence. 

Cities or towns using DNA evidence

Cities such as Florida, Connecticut, Melbourne, North Carolina, and others have discovered the greatest innovation of obtaining DNA and using it as a crime-solving tool. For example, Melbourne investigates minor crimes using DNA testing at private labs. In Melbourne, police officers test DNA to bike riders who lack two functioning lights using a cheek swab (Schmalleger, 2019). In 2015, Officer Justin Valutsky found three teenagers in a gated community sitting in a car. Since there was a case of car theft, the officer asked one of the teenagers to give a DNA sample, and Adam agreed to take a cotton swab a d gave the DNA sample. Luckily, Adam’s name was not seen in the computer system and therefore the sample was to be destroyed.

Conclusion

  Law enforcement has been using technological advancements such as telephones, CCTV cameras, lethal force devices, protective gear and other technologies to control crime.  However, the world is in a second technological revolution where scientific evidence is used to identify and solve crime cases using fingerprinting and DNA testing. Today, DNA testing is being used in the criminal justice procedure to identify the perpetrator. Scientists use substances such as blood and body tissues to detect perpetrators and solve criminal cases. The research paper finds that at the crime scene, scientists collect biological evidence such as blood, hair, and other substances such as botanical to find evidence. It is important to note that the variation in molecular genetics makes it easier to identify persons with their DNA typing. The criminal justice system, as well as civil justice, has experienced the benefits of DNA typing in that due to its reliability and validity, DNA typing is providing the scientists with sensitive information.   Today, the forensic DNA analysis has greatly improved the field of crime investigation and prevention. Even though the work of solving crimes is not only about matching suspects to DNA,  the  DNA evidence is a useful tool to identify a suspect and prove if he or she has been involved in a crime. Like a fingerprint, DNA can help scientists identify if a person was in a crime scene or not. It is evident that in addition to crime scene investigation, DNA analysis is also the best method to examine blood types, shoes, fingers, and other evidence. In general, it is important to note that all living organisms have genes that form as a result of DNA. However, every person has unique DNA and or  DNA sequences and forensic scientists use the DNA sequencing to find DNA evidence or to assess whether a  suspect was involved in crime or not.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

References

Schmalleger, F. (2019). Criminal justice today: An introductory text for the twenty-first century.

 

Pearson

 

Tilstone, W. J., Savage, K. A., & Clark, L. A. (2003). Forensic science: An encyclopedia of

history, methods and techniques. Oxford: ABC-Clio.