A criminal trial is fought on the evidence the police collect. The investigating officer decides which witnesses to record, whether to visit the spot, what to recover, and when samples go to the laboratory. The courts say his job is confined to collecting evidence (Muhammad Arshad, PLD 2011 SC 350), but the quality of what he collects decides whether the case is proved beyond reasonable doubt.

This research paper studies 103 reported judgments of the Supreme Court and the Peshawar High Court from 1972 to 2026. It covers the IO's statutory powers and their limits; the police opinion of innocence and column No. 2; delay in recording statements under section 161; the site plan and spot inspection; recoveries and mashirs; narcotics samples and the chain of custody; the case diary; failure to examine the IO; withheld evidence; the officer who is both complainant and investigator; and successive investigations.

The main finding: the centre of the law has not changed. The IO collects, the court decides, and the police opinion binds no one. What has changed is how closely the courts now test each step: the FIR, the statement, the site plan, the recovery, the sample, the register and the carrier must each be shown on paper and through a witness.

The paper is honest about the limits. It also collects the cases where a lapse was held not to be fatal, and gives a practical checklist for both the defence and the prosecution.

The full paper, with a question-and-answer summary of every judgment, is free to download:
https://arbitratorandlaw.com/resources/research/7/file

For more research papers like this one, visit the Resources page:
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Adv. Syed Zeshan Hashmi, Advocate High Court
The Arbitrator & Law Associates, Opposite Prime Hospital, Ring Road, Peshawar | 0313-4859592