Informant-investigator identity does not by itself vitiate a criminal investigation; bias or prejudice must be shown on the facts.

A criminal investigation is not automatically vitiated merely because the informant or complainant and the investigating officer are the same person. The Court held that the CrPC and the NDPS Act contain no express bar against that identity, and unfairness cannot be presumed from that fact alone. The issue must be decided on the facts of each case, with proof of real bias, prejudice, likelihood of bias, or failure of justice before the investigation is treated as invalid. The broad rule of automatic vitiation was rejected to that extent.

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Issues: (i) Whether a criminal trial is automatically vitiated when the informant or complainant also conducts the investigation; (ii) whether the issue must be decided universally or on the facts of each case, including the question of bias or prejudice.

Issue (i): Whether a criminal trial is automatically vitiated when the informant or complainant also conducts the investigation.

Analysis: The provisions governing investigation under the Code of Criminal Procedure permit an officer in charge of a police station to receive information of a cognizable offence, reduce it into writing, and investigate it. The special procedure under the NDPS Act also contains no express bar against the informant and investigator being the same person. The mere fact that the same officer registered the case and investigated it does not, by itself, establish unfairness or invalidate the prosecution. The trial is not liable to be treated as vitiated unless bias, prejudice, or a failure of justice is shown on the facts.

Conclusion: The trial is not automatically vitiated merely because the informant and the investigator are the same person.

Issue (ii): Whether the issue must be decided universally or on the facts of each case, including the question of bias or prejudice.

Analysis: Earlier decisions turning on the complainant-investigator identity were confined to their own facts. The correct approach is to examine whether the facts of the particular case disclose real bias, likelihood of bias, prejudice, or unfair investigation. A broad and unqualified rule of automatic vitiation is not warranted. The Court also held that the contrary view in Mohan Lal and similar cases could not be sustained as a general proposition of law and stood overruled to that extent.

Conclusion: The question must be decided case by case, and bias or prejudice must be established before the investigation can be treated as vitiated.

Final Conclusion: The reference was answered by holding that identity of the informant and the investigator does not, by itself, invalidate the investigation or entitle the accused to acquittal, and the contrary broad rule was rejected.

Ratio Decidendi: A criminal investigation is not vitiated merely because the informant or complainant is also the investigating officer; invalidity arises only where the facts disclose bias, prejudice, or failure of justice.

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