Fair investigation under the NDPS Act is breached when the complainant also conducts the investigation, vitiating conviction.

A prosecution under the NDPS Act is vitiated where the same person acts as complainant, seizing or apprehending officer, and investigating officer, because investigation must be fair and must also appear fair. Reading Mohan Lal, the Delhi HC held that this prohibition is not limited to cases where the informant investigates; it applies equally when the accusation and investigation are both handled by the same officer. The Court also held that proof of actual prejudice is unnecessary, since such a combination creates a real apprehension of bias and undermines Article 21 fair trial rights. On the facts, PW-1 was both complainant and investigating officer, so the conviction could not stand.

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Issues: Whether a prosecution under the Narcotic Drugs and Psychotropic Substances Act is vitiated when the complainant or investigating officer is the same person, and whether the appellant's conviction could stand in such a situation.

Analysis: The Court read the Supreme Court's decision in Mohan Lal as laying down that, especially in cases under the Narcotic Drugs and Psychotropic Substances Act where reverse burden provisions operate, the investigation must be fair and must also appear to be fair. The Court held that the prohibition is not confined to a case where the informant is the investigating officer, but extends equally to a case where the complainant, the seizing officer, or the officer who apprehended the accused is also the investigating officer. It further held that actual proof of prejudice is not required where the same person initiates the accusation and investigates it, because such a situation creates a real apprehension of bias and undermines fair trial rights under Article 21. On the facts, the Court found that PW-1 was both the complainant and the investigating officer, and rejected the attempt to shift that role to another witness.

Conclusion: The appellant's conviction was vitiated because the complainant was also the investigating officer, and the appellant was entitled to acquittal.

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