ABSTRACT
Forensic science is the application of scientific methods or expertise to criminal investigations or the examination of evidence that could be presented in court. A wide number of subjects are included in forensic science, including anthropology, animal forensics, finger prints, and DNA analysis. Forensic DNA analysis has proven important in solving crimes and identifying the perpetrators. Given that DNA is individualized and detectable in even trace amounts at crime scenes, it is often regarded as the most reliable kind of evidence. Furthermore, DNA evidence can provide unchangeable proof in cases when other forms of evidence would not be able to establish guilt beyond a reasonable doubt.
Possibly the most important development in forensic science during the past century is forensic DNA testing. DNA analysis has seen as a crucial component of forensic science that has altered how professionals investigate crimes. The field of forensic science has enormous promise for the administration of justice. The entire area of criminal investigation is changing as a result of new developments in trends and technology. From DNA analysis to biometric identification, there are countless opportunities for scientific growth.
Keywords: DNA, Forensic Science, Extraction, DNA Analysis, Forensic DNA
INTRODUCTION
Forensic science is the use of physical and natural scientific techniques to criminal and civil law cases. In addition to investigating and prosecuting crimes like drug trafficking, rape, and murder, forensic science can also be used in cases where no crime has been committed but instead a civil wrong ,such as planned pollution of the air or water or causing injuries to workers has been committed. Forensic science is one of the most important investigative techniques for cracking the case, producing relevant proof, and advancing the cause of justice. The subject of forensics is changing quickly as a result of significant technical advancements and exciting new scientific findings. However, given the incredibly bright future of forensics, we cannot claim that the field’s accomplishments are limited to where they are at this point. The Indian Supreme Court examined the value of forensic evidence in the case of Dharam Dev Yadav v. State of Uttar Pradesh, particularly in cases involving more serious and well-planned crimes.
Deoxyribonucleic acid (DNA) is important in forensic science because it may exonerate the innocent while condemning the guilty. The genetic material in DNA enables for the identification of the culprit through the processing and analysis of biological evidence found at the crime scene. Forensic DNA analysis has proven important in solving crimes and identifying the criminals. Given that DNA is individualized and detectable in even trace amounts at crime scenes, it is often regarded as the most reliable kind of evidence. Furthermore, DNA evidence can provide clear proof in cases when other forms of evidence would not be able to establish guilt beyond a reasonable doubt.The importance of forensic DNA analysis in criminal investigations has grown even more with the introduction of DNA databases. Criminals who may not have been discovered otherwise have been identified through databases made up of DNA profiles from those who have been found guilty of certain crimes or who have willingly contributed their profiles.
RESEARCH METHODOLOGY
This research work is based on secondary sources, such as criminal actions (evidence act), Bharatiya Sakshya Adhinyam, 2023, and is descriptive in form. The main goals are to compile, analyze, and derive conclusions from previously released studies, papers, and other pertinent sources. Websites and newspapers are utilized as secondary sources of information for this study.
REVIEW OF LITERATURE
The article analysis the importance of DNA Analysis in Forensic Science as evidence under criminal laws in India.A detailed study have been conducted to analyse about the importance of DNA Evidence in Forensic Science .Some of the topics reviewed are as follows.
- Importance of DNA Evidence
- The Indian Evidence Act,1872(,Bharatiya Sakshya Adhinyam,2023)
- Case study on Mukesh and Another v. State (NCT of Delhi) and Others, (2017)6 SCC 1
DISCOVERY AND HISTORY OF DNA
When people started selectively breeding animals and crops to generate healthier livestock and crops, the history of DNA began in 5000 BC. There have been numerous times throughout history where major discoveries have been made concerning DNA and heredity.
DNA was initially discovered by Swiss scientist Friedrich Miescher while examining pus from hospital dressings. Miescher created methods for obtaining DNA and established the basis for the field of genetics. As the name of Miescher faded into obscurity by the twentieth century, other scientists continued exploring the chemical properties of the molecule once called nuclein. Among them was Phoebus Levene, a Russian biochemist who made significant contributions to understanding RNA and DNA structures. He was the first to accurately determine the arrangement of RNA and DNA molecules and the sequence of the three key components of a nucleotide: phosphate, sugar, and base. Additionally, Levene identified the carbohydrate components of RNA (ribose) and DNA (deoxyribose).
Indeed, numerous fresh facts and data quickly surfaced, altering Levene’s theory. During this time, a significant discovery was made about the order of nucleotides. Levene developed Levene proposed a tetranucleotide structure where nucleotides were always connected in a fixed sequence. However, scientists later found this structure overly simplistic, recognizing that the arrangement of nucleotides in DNA and RNA is highly variable. Nevertheless, many aspects of Levene’s polynucleotide structure proved to be accurate.
Erwin Chargaff was a pivotal scientist who expanded on Levene’s work, contributing significant insights into DNA structure and paving the way for Watson and Crick’s discoveries. Curious about variations in DNA across species, Chargaff developed a groundbreaking paper chromatography technique to analyze small quantities of organic material (Chargaff, 1950). His investigations challenged Levene’s fixed nucleotide sequence model, revealing that the nucleotide composition of DNA varies between species.
Chargaff also discovered universal principles of DNA that apply across organisms and tissue types. Despite compositional differences, he found consistent patterns in DNA’s structural properties, highlighting its fundamental role in all forms of life. These findings were instrumental in shaping the understanding of DNA’s complexity and variability.
Watson and Crick’s finding was also enabled by recent breakthroughs in model building, or the creation of hypothetical three-dimensional structures based on known chemical distances and bond angles, a technique pioneered by American biologist Linus Pauling. In reality, Watson and Crick were concerned that they might be “scooped” by Pauling, who had suggested an alternative model for the three-dimensional structure of DNA two months before them. In the end, Pauling’s prognosis proved inaccurate.
Scientists have expanded on Watson and Crick’s foundational model of DNA by identifying three distinct conformations of the double helix, each with unique geometries and dimensions. The most common form, B-DNA, is predominant in living cells and aligns with the structure proposed by Watson and Crick, as depicted in most double helix diagrams. Two alternative conformations also exist: A-DNA, a shorter and wider form typically found in dehydrated DNA samples, and Z-DNA, a left-handed helix that forms temporarily in response to specific biological activities.
Z-DNA, first identified in 1979, was largely overlooked for decades. Recent research, however, has revealed its importance, showing that certain proteins bind tightly to Z-DNA. This discovery suggests that Z-DNA plays a critical role in biological processes, particularly in resistance to viral infections (Rich & Zhang, 2003).
Watson and Crick were the first to accurately describe the intricate double-helical structure of DNA, though they were not its discoverers. Their groundbreaking model was built upon the foundational work of several scientists who preceded them. Key contributors included Friedrich Miescher, who first identified DNA as a distinct molecule; Phoebus Levene, who clarified the structure of nucleotides; and Erwin Chargaff, whose findings on nucleotide composition provided crucial insights. Watson and Crick’s achievements were a culmination of decades of research, highlighting the collaborative nature of scientific discovery.
DNA ANALYSIS AND EXTRACTION
DNA extraction is a fundamental process in biotechnology, serving as the foundation for various applications, from routine medical diagnostics and treatment planning to advancing basic scientific research. This process is essential for isolating and purifying DNA to study its unique properties, such as size, structure, and function. It plays a critical role in drug development, diagnostic tool creation, and understanding the genetic basis of diseases. Beyond healthcare, DNA extraction is indispensable in paternity testing, detecting environmental pathogens, genome sequencing, and forensic science. In particular, forensic DNA analysis has become the gold standard for investigative techniques, often surpassing other forensic methods due to its accuracy and reliability. Its immense versatility makes it a powerful tool across multiple disciplines.
DNA extraction involves isolating DNA from proteins, membranes, and other biological components through a series of steps: lysis, precipitation, and purification (Rice, 2018).
The first step, lysis, involves breaking open cells to release DNA by destroying the cell membrane. The second step, precipitation, isolates the DNA from proteins and other cellular materials using ethanol or isopropanol, resulting in pure DNA. Finally, during purification, the DNA is separated from the aqueous phase, redissolved in water for easy handling and storage, and purified for use in further applications.
Isolating pure nuclear and/or mitochondrial DNA from both forensic specimens (blood, sperm or saliva stains, hairs, muscle, bones, teeth, etc.) and reference samples (bucal swabs, blood spots on FTA, or liquid blood) is an important step in DNA profiling. Advances in forensic DNA extraction methods have tried to increase the efficiency of pure DNA recovery (free of polymerase chain reaction (PCR) inhibitors) and automate the process for high-throughput analysis while keeping the DNA molecule’s integrity.
Currently, forensic laboratories use three main categories of verified DNA extraction methods based on purification strategies: organic extraction (phenol-chloroform), solid-phase extraction (silica-based), and ionic chelating resins (Chelex). These methods can be adapted to specific sample types by employing tailored processes that integrate basic DNA isolation principles. Examples include differential lysis for selective sperm cell extraction, specialized protocols for extracting DNA from bones and teeth, purification from biological samples on FTA paper, and isolating specific cell types through laser-capture microdissection. Automated DNA extraction using robotic platforms is also common in forensic labs, enabling high-throughput sample preparation while minimizing human error and enhancing tracking and consistency. Forensic laboratories maintain stringent quality standards for DNA extraction, including contamination prevention measures and the use of positive and negative controls to ensure process reliability.
Since Friedrich Miescher carried out the first DNA extraction in 1869, scientists have made incredible strides in creating extraction techniques that are more dependable, simpler, quicker, more economical, and generate better yields. Improved, more dependable and effective methods have contributed to the understanding of the human genome and helped give rise to new scientific disciplines like gene editing and personalized medicine. However, because of their limitations in generating yields with the best possible purity and ease of use, it appears that there is currently no one technique that can be used in all DNA extraction scenarios.
DNA ANALYSIS AND FORENSIC SCIENCE
The most essential procedural and evidentiary standards governing the use of forensic DNA evidence, highlights scientific fact issues that have been litigated, and evaluates legal developments.
All forensic techniques for individualization, such as DNA profiling, blood grouping, voice spectrograms, hair and fiber comparisons, dental impressions, bullet striations, fingerprints, and neutron activation analysis, depend on the ability to reasonably match samples in terms of traits that can aid in differentiating one source from another. For such evidence to be admissible in court, precise physical characteristic assessment and comparison must be made possible by methods recognized by science. Similar to this, concluding that well-executed comparisons can reveal potential sources necessitates a scientific foundation.
The admissibility of scientific data in criminal cases depends on several factors: whether the evidence is relevant to proving or disproving a fact material to the case under applicable law, the qualifications of the expert presenting it, whether the data is derived using scientifically valid methods, and whether its probative value outweighs potential unfair prejudice or excessive time consumption. These principles form the basis for evaluating the acceptability of scientific evidence, including DNA evidence. This discussion also examines pretrial and trial procedures that can help courts make informed decisions about admissibility while enhancing the quality and application of scientific evidence during trials. Key procedural issues include addressing defendants’ requests for discovery, retesting, or expert assistance, which are often intertwined with broader evidentiary considerations.
Forensic scientists can use DNA profiles to identify offenders and establish paternity. A DNA profile resembles a genetic fingerprint. Every person has a distinct DNA profile, making it extremely beneficial for identifying those engaged in a crime. The results of DNA profiles can be utilized in court. For example, samples gathered at a crime scene may match the DNA of a suspect. This might be used to show that the suspect was there at the crime site, but it does not necessarily establish that the suspect committed the crime.
DNA evidence is rarely the only foundation for a prosecution case. It is most effective when combined with additional evidence, such as fingerprints, footprints, crime scene examinations, and eyewitness testimony. Blood splash patterns (which reflect the direction of the injury) and microbiological information (which may offer hints as to the time of death) are examples of biological evidence that may be obtained.
These days, hundreds of thousands of DNA tests are used by hundreds of forensic laboratories in the public and private sectors, in addition to paternity testing facilities. Law enforcement has benefited greatly from computer databases that contain DNA profiles of convicted criminals, biological samples taken from crime scenes, and information on people who have been detained for a crime. These databases help solve crimes and penalize offenders according to the particular offenses they have committed.
Furthermore, the use of forensic DNA testing has had results beyond only holding the guilty accountable for their actions. Additionally, the evidence has cleared innocent people of crimes they did not commit. Prior to the use of DNA typing techniques, inmates were wrongfully convicted due to the use of unreliable witnesses or the results of different kinds of evidence.
However, more than 200 of these people—including death row inmates—were cleared thanks to the effectiveness of post conviction DNA testing using specimens that were kept for several years. For decades, courts, lawyers, and police have successfully used DNA evidence from crime scenes to convict the guilty and clear the innocent. As a result, DNA evidence is frequently requested from crime scenes.
In Mukesh and Another v. State (NCT of Delhi) and Others , the prosecutrix was gang-raped and killed, and the appellants were found guilty and given the death penalty. The prosecution used DNA evidence in addition to other pieces of evidence to convict the appellants. The significance of DNA evidence was deliberated by the Supreme Court during its confirmation of the conviction and punishment.
LIMITATIONS OF DNA EVIDENCE
DNA evidence is strong, but it is not without limitations. One limitation results from misconceptions regarding the actual importance of a DNA match. The simple fact that a suspect’s DNA matches that of a crime scene does not establish guilt. Forensic experts would prefer to talk about likelihood instead.
Even more concerning are DNA fraud instances, in which criminals plant fake DNA samples at a crime scene. In 1992, Canadian physician John Schneeberger planted fake DNA evidence in his own body to allay suspicions in a rape case. The problem extends beyond the use of someone else’s DNA in fictitious plants. Utilizing profiles stored in one of the DNA databases, researchers at the Israeli company Nucleix recently disclosed that they could generate a DNA sample without obtaining any tissue samples from the individual.
In criminal cases involving DNA evidence, it is imperative to have an expert witness present in court to clarify the results. On the other hand, a dishonest expert might make matters more difficult. Furthermore, there are several opportunities for contamination or manipulation along the DNA evidence’s transit from the crime scene to the lab. A minor problem with mixed DNA profiles is that they might be difficult to understand when a sample comes from many individuals.
The other side could challenge the validity of the evidence by challenging the forensic analysts’ handling and preservation techniques.Ultimately, not every situation lends itself to DNA testing as a feasible solution.
It may be challenging to produce a complete DNA profile and the test may only provide a partial profile in situations when samples contain extremely low levels of DNA, are subjected to harsh environmental conditions, or are not adequately kept. Partial profiles, however, can still be useful in deciding whether or not to include a certain person in the inquiry.
SUGGESTIONS
DNA fingerprinting has been utilized in India to prove the guilt of suspects and prisoners in legal proceedings. Nonetheless, technology may be just as helpful in proving a suspect or convicted person’s innocence. India is still not utilizing this technology to protect citizens from being wrongfully convicted. There are also very few provisions in the Indian legal system that discuss DNA. Whenever it mentions anything about collecting DNA samples from the victim and accused, it simply discusses the protocols and circumstances involved.
However, there are said to be 40,000 unidentified bodies in India. Every year, about a lakh youngsters disappear. All of these may profit from the application of DNA fingerprinting technology if the rules are more well-defined. The Indian DNA bill now in effect aims to solve issues with data security, quality, and correctness. Its goal is to create a DNA Regulatory Board that will set policies, norms, and practices for the creation and operation of DNA data banks and testing facilities. The nation expects that the measure closes many of the existing loopholes and makes DNA fingerprinting technology a normal practice in court proceedings, rather than limited to a few exceptional instances.
CONCLUSION
Over the past few decades, forensic DNA analysis has advanced dramatically, becoming more rapid, affordable, and accessible to the point that DNA swabs are now often used for even minor offenses, creating a massive backlog of forensic evidence. Over the ensuing decades, forensic analysis’s skills and capacity are probably going to keep growing, becoming more affordable, quicker, and sensitive.
Although operation costs are a barrier to widespread use, fully automated DNA profiling devices have been produced that can extract, amplify, segregate, and genotype samples in less than 90 minutes. These gadgets are said to be installed in police stations so that people can be charged with a crime and they can be detained lawfully.
PCR amplification, which needs many heating and cooling cycles to produce enough DNA for analysis, is currently the most time-consuming step in DNA analysis. Many techniques for accelerating PCR amplification are being developed, such as micro-PCR apparatuses that operate with lower liquid volumes and may thus heat or cool more rapidly.
Next-generation sequencing (NGS), one of the futuristic developments in DNA sequencing technology, has been shown to improve forensic analysis’s precision and effectiveness.
Although DNA analysis and testing is a crucial component of forensic investigations, it can occasionally take a long time. By enabling investigators to extract DNA from samples taken from the crime scene and prepare the samples for additional analysis and inspection, automated systems in forensics aid in the investigation of criminal activity. In addition, the technology allows an examiner to divide DNA evidence into pieces, giving investigators the most precision and speed possible.
In the future, it may be possible to estimate an individual’s genetic profile using known phenotypic traits such as height, ethnicity, eye and hair color, and other hereditary characteristics, even without a reference sample. Additionally, because bacteria can be released through various pathways, including breath, and because microbiomes are highly individualistic, microbial DNA analysis could become a valuable tool in criminal investigations. Microbial DNA could potentially help place individuals at crime scenes, as it is often widespread and difficult to remove. In some cases, the microbiome may provide more reliable touch evidence than traditional DNA analysis. It could also offer insights into a person’s past locations, the nature of their death, and the time that has elapsed since their passing.
This article is written by Adheena Printo C (Bharata Mata School Of Legal Studies)