Dna Evidence Analysis
DNA evidence refers to the use of deoxyribonucleic acid profiling to identify individuals involved in a crime. It is considered one of the most reliable forms of forensic evidence because every individual’s DNA sequence is unique (except identical twins). DNA evidence is commonly used in cases involving sexual assault, murder, and paternity disputes.
Process of DNA Evidence Analysis:
Collection: Biological samples (blood, hair, skin cells, semen, saliva) are collected carefully to avoid contamination.
Extraction: DNA is extracted from the cells in the collected samples.
Quantification: The amount of DNA is measured to ensure there is enough for testing.
Amplification (PCR): The Polymerase Chain Reaction (PCR) technique amplifies specific regions of the DNA to generate sufficient material for analysis.
Profiling: Specific regions of DNA called STRs (Short Tandem Repeats) are analyzed. These vary greatly among individuals.
Comparison: The DNA profile from the crime scene is compared with the DNA profiles of suspects or databases.
Interpretation: Experts interpret the probability that the DNA matches or excludes suspects.
Presentation in Court: DNA evidence is presented as expert testimony with the statistical likelihood of a match.
Landmark Cases Involving DNA Evidence
1. State of Punjab vs. Gurmit Singh and Others (1996)
Background: This was one of the earliest cases in India where DNA evidence was used.
Facts: The case involved the murder of a young woman. The prosecution relied on DNA evidence to link the accused to the crime.
Significance: The Supreme Court of India accepted DNA profiling as valid scientific evidence for the first time in Indian jurisprudence. It laid down the foundation for DNA evidence's admissibility under the Indian Evidence Act.
Impact: This case opened the door for the routine use of DNA evidence in Indian criminal trials.
2. Hussainara Khatoon vs. State of Bihar (1980) - Contextual Relevance
Background: While this case primarily dealt with the rights of prisoners, it indirectly influenced forensic investigations by emphasizing fair trials and due process.
Relevance to DNA Evidence: The principles of fair trial and scientific evidence paved the way for the acceptance of DNA evidence to ensure just convictions.
Outcome: It emphasized the judiciary’s role in scrutinizing scientific evidence to protect individual rights.
3. People vs. Wesley (California, USA) (1984)
Background: This was one of the first criminal cases globally to use DNA evidence for conviction.
Facts: Wesley was convicted of sexual assault based on blood group analysis initially, but DNA profiling later conclusively linked him to the crime.
Significance: This case is internationally recognized for establishing the credibility of DNA evidence and its forensic use.
Impact: It revolutionized criminal investigations worldwide, demonstrating DNA’s power to conclusively identify or exclude suspects.
4. Michael Morton Case (Texas, USA) (2011)
Background: Morton was wrongfully convicted of his wife’s murder based on circumstantial evidence.
Facts: After spending nearly 25 years in prison, DNA testing on evidence from the crime scene proved that another man was the real culprit.
Significance: This case underscores how DNA evidence can be used not only for convictions but also for exonerating innocent people.
Impact: It highlighted the need for careful handling of evidence and the power of modern DNA testing in correcting miscarriages of justice.
5. State of Kerala vs. Rajeevan (2010)
Background: In this Indian case, DNA evidence played a crucial role in identifying the accused in a sexual assault case.
Facts: Biological samples found on the victim’s body were matched to the accused using DNA profiling.
Judgment: The Kerala High Court accepted the DNA report as conclusive evidence of the accused’s involvement.
Significance: Reinforced the credibility of DNA evidence in Indian courts and established its use in sexual assault cases.
Summary
DNA evidence is a powerful tool in modern criminal investigations and courts. It provides:
Scientific certainty in linking suspects to crimes.
The ability to exonerate innocent individuals.
A strong, objective basis for convictions.
The case laws mentioned show how courts have progressively accepted and relied on DNA evidence:
State of Punjab vs. Gurmit Singh: First acceptance of DNA evidence in India.
People vs. Wesley: Landmark global case establishing DNA's credibility.
Michael Morton: DNA used for exoneration.
State of Kerala vs. Rajeevan: DNA evidence in sexual assault convictions.
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