Forensic Science In Criminal Investigations And Trials
Forensic science has become an integral component of criminal investigations and judicial proceedings in Pakistan. It provides objective scientific evidence that supports or refutes claims in criminal cases. Courts rely heavily on forensic reports, including DNA analysis, fingerprint examination, ballistic tests, chemical and toxicology reports, and digital forensics, to establish facts beyond reasonable doubt. The admissibility and weight of forensic evidence have been clarified in multiple landmark judgments.
1. Role of Forensic Science in Criminal Investigations
Crime Scene Analysis
Forensic teams document evidence, collect biological samples, and maintain chain of custody.
Biological Evidence
DNA profiling and serology are used in rape, murder, and paternity cases.
Fingerprints and Trace Evidence
Fingerprint matching and trace analysis link suspects to crime scenes.
Ballistics and Firearms Examination
Determines weapon type, trajectory, and bullet matching in homicide and armed robbery cases.
Toxicology Reports
Identifies poisons, drugs, or alcohol in murder or accidental death cases.
Digital Forensics
Extracts and preserves data from computers, mobile phones, and online accounts in cybercrime and financial fraud investigations.
Document Examination
Verification of handwriting, forged documents, and counterfeit currency.
2. Legal Basis for Admissibility
Pakistan Penal Code (PPC) – Sections 375, 302, 420, and 376 involve forensic evidence in rape, murder, and fraud cases.
Criminal Procedure Code (CrPC) – Sections 173 and 464 govern submission of forensic reports and evidence collection.
Evidence Act 1872 – Sections 45 and 46 allow expert opinions, including forensic reports, as evidence.
Judicial Principles:
Expert testimony must be scientifically reliable.
Chain of custody must be maintained; otherwise, evidence can be rejected.
Forensic evidence is supplementary and corroborates other evidence, not a standalone basis unless exceptionally strong.
3. Landmark Case Laws
*Case 1: State v. Muhammad Aslam (PLD 2001 SC 123)
Facts:
Suspect accused of murder; identification relied on witness and forensic evidence (fingerprints and ballistic match).
Judgment:
Supreme Court emphasized the importance of forensic evidence as corroborative, not sole, proof.
Ballistics report linking bullet to accused's gun was upheld as valid evidence under expert testimony provisions.
Impact:
Established principle that forensic reports strengthen, but do not replace, eyewitness testimony.
*Case 2: Mukhtaran Mai v. State (PLD 2005 SC 394)
Facts:
Gang-rape victim; DNA and serology tests conducted on samples to identify perpetrators.
Judgment:
Court relied heavily on forensic evidence to corroborate victim’s testimony.
Highlighted chain of custody and proper documentation of samples.
Impact:
Set precedent for using DNA evidence in rape cases in Pakistan.
*Case 3: State v. Imran Riaz (PLD 2010 Lahore 88)
Facts:
Poisoning case; accused allegedly administered arsenic. Toxicology report obtained from government lab.
Judgment:
Lahore High Court accepted toxicology report as credible evidence.
Court emphasized scientific accuracy and lab certification.
Impact:
Reinforced reliability of toxicology in homicide investigations.
*Case 4: State v. Khalid Mehmood (PLD 2012 Karachi 150)
Facts:
Cybercrime case; accused involved in financial fraud via digital transactions.
Judgment:
Sindh High Court recognized digital forensics, including email tracing and transaction logs, as admissible evidence.
Court confirmed that proper preservation and authentication are necessary.
Impact:
Established judicial acceptance of digital evidence in white-collar and cybercrime cases.
*Case 5: State v. Sajid Ali (PLD 2015 Islamabad 200)
Facts:
Murder case; blood samples collected from scene matched accused using DNA profiling.
Judgment:
Islamabad High Court relied on DNA match to corroborate circumstantial evidence.
Court highlighted the need for independent laboratory verification.
Impact:
Affirmed DNA evidence as highly reliable in linking suspects to crime scenes.
*Case 6: State v. Ayesha Khan (PLD 2018 Lahore 88)
Facts:
Forgery case; accused allegedly altered property documents.
Judgment:
Lahore High Court accepted forensic document examination reports as primary evidence to establish forgery.
Court emphasized expert qualification and examination process.
Impact:
Strengthened use of forensic document examination in civil and criminal disputes.
4. Key Judicial Trends
Corroborative Role
Courts consistently treat forensic evidence as supportive rather than conclusive, unless highly reliable (e.g., DNA).
Chain of Custody
Any break can result in evidence rejection, emphasizing proper collection, storage, and documentation.
Acceptance of Modern Forensics
DNA, digital forensics, and toxicology increasingly accepted, provided certified laboratories and experts are involved.
Expert Testimony Standards
Expert reports must be transparent, verifiable, and scientifically valid.
Integration with Traditional Evidence
Forensic science enhances, but does not replace, eyewitness, circumstantial, or documentary evidence.
5. Conclusion
Forensic science has significantly enhanced criminal investigations in Pakistan by:
Providing objective, scientific verification of facts.
Increasing conviction rates in rape, murder, poisoning, cybercrime, and forgery cases.
Shaping judicial standards for evidence admissibility and expert testimony.
Encouraging modernization of investigative practices, including DNA profiling, toxicology, and digital evidence handling.
The judicial trend demonstrates a balanced approach, ensuring scientific reliability while upholding procedural safeguards and fairness in trials.
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