Forensic analysis of seized biological samples

Introduction

Forensic analysis of seized biological samples refers to the scientific examination of biological materials collected or recovered during criminal investigations, regulatory inspections and legal proceedings. These samples may include blood, saliva, tissue, hair, microorganisms, plant materials, animal remains and genetically modified biological substances.

In biotechnology-related investigations, forensic analysis may be required to identify genetically engineered organisms, detect biological contamination, establish the origin of biological materials or investigate unauthorised handling of regulated microorganisms.

The purpose of forensic examination is to produce scientifically reliable evidence that can assist investigating agencies, regulatory authorities and courts. In India, such investigations are governed by criminal procedure laws, evidence legislation, forensic laboratory standards and applicable environmental and biotechnology regulations.

Meaning and objectives of forensic biological analysis

Forensic biological analysis involves the scientific identification, examination and interpretation of biological evidence.

Its major objectives include:

Identifying the biological origin of seized samples.

Establishing the presence of specific microorganisms or biological substances.

Detecting genetic material and identifying relevant genetic characteristics.

Examining possible contamination or biological modification.

Establishing connections between biological samples and investigated activities.

Preserving evidence for judicial proceedings.

Supporting investigations involving public health, environmental violations and biotechnology-related offences.

Biological evidence must be collected and examined carefully because contamination, degradation and improper storage can affect the reliability of scientific findings.

Legal framework in India

1. Bharatiya Nagarik Suraksha Sanhita, 2023

The BNSS provides the procedural framework for criminal investigations and the collection of evidence.

Section 176 deals with the procedure for investigation by police officers. Section 185 provides powers concerning searches by police officers during investigations, subject to statutory conditions.

Section 349 provides for examination of specimen signatures, handwriting, finger impressions and voice samples in accordance with its requirements.

These provisions may become relevant when biological evidence is collected during criminal investigations, alongside other applicable legal procedures.

2. Bharatiya Sakshya Adhiniyam, 2023

The Bharatiya Sakshya Adhiniyam governs the admissibility and evaluation of evidence in judicial proceedings.

Section 39 deals with opinions of experts. Scientific opinions concerning DNA, microbiology, genetic testing and other forensic examinations may be considered under this provision.

Sections 61–63 address electronic and digital records and their admissibility, subject to applicable conditions.

Laboratory reports and digital records relating to biological examinations must satisfy the relevant evidentiary requirements.

3. Code of Criminal Procedure, 1973

The Code of Criminal Procedure, 1973, has been replaced by the BNSS for proceedings governed by the new criminal procedure framework from 1 July 2024, subject to applicable transitional provisions.

Older judicial decisions interpreting the CrPC may remain relevant when understanding equivalent procedural principles.

4. Environment (Protection) Act, 1986

This Act is relevant where seized biological materials involve hazardous substances, genetically engineered organisms or environmental contamination.

The Environment (Protection) Rules, 1989, establish regulatory requirements concerning the handling and control of specified genetically engineered organisms and hazardous microorganisms.

5. Biological Diversity Act, 2002

The Act regulates access to biological resources and associated traditional knowledge, subject to its statutory provisions and exemptions.

Forensic examination of seized biological materials may help establish their identity, origin or relationship with regulated biological resources.

Major stages of forensic analysis

1. Collection and seizure of biological samples

The first stage involves identifying and collecting relevant biological materials during an investigation.

The collection process must be legally authorised and properly documented. Investigators should record the location, date, time, circumstances of seizure and identity of the collecting officer.

2. Preservation and storage

Biological materials may deteriorate because of temperature, moisture, microbial activity or improper handling.

Appropriate storage and preservation arrangements are necessary to maintain sample integrity. Each sample should be separately identified and protected against contamination.

3. Chain of custody

Chain of custody refers to the documented history of evidence from collection until its presentation in court.

It establishes who collected, handled, transported, stored and examined the biological material.

Important records include:

Sample identification number.

Date and location of collection.

Name of the responsible investigating officer.

Details of packaging and sealing.

Transfer and receipt records.

Laboratory examination details.

Storage and disposal records.

An incomplete chain of custody may weaken the evidentiary value of a sample.

4. Laboratory examination

Qualified forensic experts examine biological materials using appropriate validated scientific methods.

Depending on the nature of the sample, examination may involve DNA analysis, microscopy, biochemical testing, microbiological identification or genetic sequencing.

5. Interpretation of scientific results

Laboratory findings must be interpreted carefully. The presence of a particular genetic sequence does not necessarily establish the presence of a living organism or prove that a particular person committed an offence.

Experts must explain the limitations, uncertainties and scientific significance of their findings.

6. Preparation of forensic reports

The final forensic report should identify the samples examined, analytical methods used, observations, results and conclusions.

It should also mention relevant limitations, possible contamination concerns and the qualifications of the examining expert.

Important technologies used in forensic biological examination

1. DNA profiling

DNA profiling helps identify biological relationships and compare biological samples recovered during investigations.

2. Polymerase Chain Reaction (PCR)

PCR is used to identify specific genetic sequences in biological materials. It may assist in examining microbial or genetic evidence.

3. DNA sequencing

Sequencing techniques help examine genetic characteristics and identify relevant biological organisms.

4. Microscopy

Microscopic examination helps identify cellular structures, tissues and certain microorganisms.

5. Mass spectrometry

This analytical technology may assist in identifying biological compounds, proteins and chemical substances associated with biological samples.

6. Bioinformatics

Bioinformatics tools help analyse genetic datasets and compare biological sequences with scientifically established reference databases.

Important case laws

1. State of Bombay v. Kathi Kalu Oghad (1961)

The Supreme Court examined the constitutional protection against self-incrimination under Article 20(3).

It distinguished between testimonial compulsion and the collection of physical evidence such as fingerprints and handwriting specimens.

The judgment is important when considering the constitutional limits of collecting physical evidence during criminal investigations.

2. Selvi v. State of Karnataka (2010)

The Supreme Court examined the legality of involuntary narco-analysis, polygraph examinations and brain-mapping techniques.

The Court held that involuntary administration of these techniques violates constitutional protections under Articles 20(3) and 21.

The judgment establishes important safeguards concerning bodily autonomy, personal liberty and scientific investigative methods.

3. Santosh Kumar Singh v. State through CBI (2010)

The Supreme Court considered forensic and medical evidence in a criminal investigation involving DNA-related questions.

The judgment demonstrates the importance of evaluating scientific evidence alongside other facts and circumstances of a case.

4. Mukesh v. State (NCT of Delhi) (2017)

The Supreme Court examined extensive forensic and scientific evidence in the Delhi gang-rape and murder case.

The judgment illustrates the evidentiary importance of DNA analysis, medical examinations and expert reports in criminal proceedings.

5. Tomaso Bruno v. State of Uttar Pradesh (2015)

The Supreme Court discussed the importance of scientific and electronic evidence in criminal investigations.

The judgment emphasised that relevant scientific evidence should be properly collected and considered when determining the facts of a criminal case.

Challenges in forensic analysis

Forensic examination of biological samples faces several scientific and legal challenges.

Sample contamination: Improper collection or handling may affect the reliability of results.

Biological degradation: Some samples deteriorate during storage or transportation.

Laboratory limitations: Inadequate equipment and technical expertise may affect examination quality.

Interpretation errors: Scientific findings may be misunderstood or presented without sufficient explanation.

Chain-of-custody disputes: Missing documentation may create questions about sample authenticity.

Privacy concerns: Genetic information may reveal sensitive personal information and requires appropriate legal safeguards.

Recommendations for strengthening forensic systems

India should strengthen biological forensic infrastructure through improved laboratory accreditation, scientific training and standardised evidence-management procedures.

Important measures include:

Ensuring properly documented collection and seizure procedures.

Maintaining secure sample storage and traceability systems.

Using validated scientific testing methods.

Strengthening forensic laboratory independence.

Training investigators in biological evidence management.

Maintaining complete chain-of-custody documentation.

Protecting personal genetic information.

Ensuring that forensic conclusions clearly explain scientific limitations.

Conclusion

Forensic analysis of seized biological samples is an important component of modern criminal investigation, biotechnology regulation and environmental enforcement. It helps establish biological identity, detect contamination and produce scientific evidence for judicial proceedings. In India, the Bharatiya Nagarik Suraksha Sanhita, 2023, Bharatiya Sakshya Adhiniyam, 2023, Environment (Protection) Act, 1986, and Biological Diversity Act, 2002, provide relevant legal frameworks. Judicial decisions such as Selvi v. State of Karnataka and State of Bombay v. Kathi Kalu Oghad establish important principles concerning scientific evidence, constitutional rights and investigative procedures. Reliable forensic examination ultimately depends on lawful collection, proper preservation, documented chain of custody and scientifically defensible reporting.