Guidelines for DNA Evidence Management

Source: The Indian Express 

Introduction 

The Supreme Court of India on July 2025 issued landmark guidelines in case of Kattavellai @ Devakar v. State of Tamil Nadu for the standardized management of DNA evidence in criminal investigations. These guidelines emerged from a case where faulty procedural handling of DNA evidence led to the acquittal of a death row convict. The Court states that there is a critical need for scientifically sound and tamper-proof processes in handling DNA evidence to maintain its integrity and reliability in the justice delivery system. 

What are the Background of Kattavellai @ Devakar v. State of Tamil Nadu Case? 

• The case originated from the brutal murder of a young couple and rape of the female victim at Suruli Falls, Tamil Nadu in May 2011.  
• The appellant, Kattavellai @ Devakar, was sentenced to death by the trial court under Sections 302, 376, and 397 of the Indian Penal Code,1860 with the conviction upheld by the Madras High Court. 
• The prosecution's case rested entirely on circumstantial evidence, primarily DNA evidence linking biological samples from the crime scene to the accused. 
• The Supreme Court found multiple procedural deficiencies that rendered the DNA evidence unreliable.  
• Critical lapses included the post-mortem being conducted in the open, absence of proper chain of custody documentation, unexplained delays in submitting samples to forensic laboratories (41 days delay), unclear storage conditions, and gaps in documentation regarding sample handling and transfer between different custody holders. 
• The Court noted that despite DNA evidence being present, it had to be discarded due to improper collection, sealing, storage, and processing methods.  
• The investigation was characterized as fundamentally faulty, with the Court observing that "a common thread running through the entire process was that of faulty investigation." 

What are the Court Observations? 

• The Supreme Court made several critical observations regarding the state of DNA evidence handling in India.  
• The Court expressed concern about the absence of uniform procedures for DNA evidence collection and use despite existing protocols, which critically affected investigations. 
• Justice Karol, writing for the bench, noted that DNA evidence, while highly reliable when properly handled, becomes worthless when procedural deficiencies compromise its integrity. 
• The Court observed that DNA profiles have tremendous impact on criminal investigations, but their validity and reliability depend entirely on quality control and procedures both inside and outside laboratories.  
• The Court observed with sadness that numerous cases require rejection of DNA evidence due to improper handling during collection, transit, and laboratory analysis. 
• The judgment states that the lack of common procedures across states was concerning, noting that while 'Police' and 'Public Order' are state subjects, this cannot permit differing procedures for sensitive evidence like DNA.  
• The Court stressed that procedural aspects aid the sanctity of evidence and must be standardized regardless of regional variations. 

What are the Supreme Court Guidelines for DNA Evidence? 

The Supreme Court issued four comprehensive guidelines to be followed in all cases involving DNA evidence: 

• Guideline 1 - Collection and Documentation:  
  • DNA samples must be collected with due care and proper packaging. Documentation shall include FIR number and date, sections and statutes involved, details of investigating officer and police station, and requisite serial numbers.  
  • The collection document must bear signatures and designations of the medical professional present, investigating officer, and independent witnesses. 
  • While the absence of independent witnesses shall not compromise evidence collection, efforts to secure witnesses and reasons for inability must be recorded. 
• Guideline 2 - Transportation and Timeline:  
  • The investigating officer bears responsibility for transporting DNA evidence to the police station or hospital concerned. Samples must reach the forensic science laboratory within 48 hours of collection.  
  • Any delay beyond this timeline requires recording reasons in the case diary. Throughout the process, requisite efforts must be made to preserve samples according to their specific nature and requirements. 
• Guideline 3 - Storage and Handling:  
  • During storage pending trial or appeal, no DNA package shall be opened, altered, or resealed without express authorization from the trial court.  
  • Such authorization requires a statement from a qualified medical professional confirming no negative impact on evidence sanctity and court assurance that the step is necessary for proper investigation or trial outcome. 
• Guideline 4 - Chain of Custody:  
  • From collection to final disposition (conviction or acquittal), a Chain of Custody Register must be maintained documenting every movement of evidence with counter-signatures and reasons.  
  • This register must be appended to the trial court record.  
  • Failure to maintain proper chain of custody renders the investigating officer responsible for explaining lapses. Directors General of Police of all states must prepare sample forms and ensure district-wide implementation. 

Is DNA Evidence Always Conclusive in Criminal Trials? 

• DNA evidence represents one of the most significant advances in forensic science and criminal investigation.  
• DNA profiling helps identify individuals based on their unique genetic characteristics by comparing biological samples from crime scenes (blood, semen, saliva, hair) with reference samples from suspects or victims. When profiles match across sufficient genetic markers, findings can be presented as crucial court evidence. 
• However, DNA evidence is only of probative value and must be properly handled to maintain reliability.  
• The Supreme Court noted that DNA evidence has led to logical conclusions in numerous cases worldwide and has also exonerated wrongly convicted individuals. 
• Technology's advancement makes it a powerful tool, but its effectiveness depends entirely on proper procedural compliance. 
• Courts have consistently held that DNA evidence, while largely dependable, can be rejected when proper methods and procedures are not followed in collection, sealing, storage, and employment.  
• Recent Supreme Court cases like Manoj v. State of M.P.,2022, Prakash Nishad v. State of Maharashtra,2023 and Rahul v. State,2022 demonstrate instances where DNA evidence was rejected due to procedural lapses, contamination possibilities, or inadequate chain of custody maintenance. 
• The Court emphasized that quality control and procedures outside laboratories matter equally in ensuring optimal results from collected samples. DNA samples must remain in pristine, hygienic, and biologically suitable conditions throughout the entire process from collection to analysis. 

What are the Legal Provisions in India?

• DNA evidence in India is governed by various legal provisions and procedural frameworks.  
• The Indian Evidence Act, 1872, particularly Sections 25, 26, and 27, governs the admissibility of statements and confessions, with Section 27 allowing disclosure statements leading to recovery of evidence. 
• The Code of Criminal Procedure, 1973, provides procedural framework for evidence collection and handling. 
• The Constitution of India, under Article 21, guarantees the right to life and personal liberty, which includes the right to fair trial and protection against wrongful conviction.  
• The Supreme Court has recognized that procedural lapses in evidence handling can violate these fundamental rights. 
• Various government bodies have issued standard operating procedures for DNA evidence handling, including the Directorate of Forensic Science Service, Ministry of Home Affairs, Central Forensic Science Laboratory guidelines, and LNJN National Institute of Criminology and Forensic Science procedures. 
• The lack of uniformity across states necessitated the Supreme Court's intervention to establish binding guidelines. 
• The Indian Penal Code, 1860, defines various offences where DNA evidence becomes crucial, particularly in cases involving murder (Section 302), rape (Section 376), and other serious crimes. 
• The Court noted that despite existing protocols, the absence of uniform procedures critically affected investigations and required judicial intervention to ensure standardization. 

Conclusion 

The Supreme Court’s guidelines mark a major step forward in improving how DNA evidence is managed in criminal cases across India. These rules set clear and uniform standards for collecting, storing, and handling DNA evidence to avoid mistakes that have earlier led to its rejection in court. The Court stressed the importance of keeping a proper chain of custody, processing evidence quickly, and maintaining accurate records. These steps will help ensure that DNA evidence remains reliable and useful in court, while also protecting the legal rights of accused persons. By following these guidelines, the criminal justice system can prevent wrongful convictions caused by poor handling of scientific evidence.