Following are the key principles, summarized recently in Karakkattu Muhammed Basheer v. The State of Kerala [2024] 11 S.C.R. 498 : 2024 INSC 838, which act as a guide for the courts to come to a conclusion with regard to the guilt of an accused in cases which are solely dependent on the circumstantial evidence:
That the chain of events needs to be so established that the court has no option but to come to one and only one conclusion i.e. the guilt of the accused person. If an iota of doubt creeps in at any stage in the sequence of events, the benefit thereof should flow to the accused. Mere suspicion alone, irrespective of the fact that it is very strong, cannot be a substitute for a proof. The chain of circumstances must be so complete that they lead to only one conclusion that is the guilt of the accused. Even in the case of a conviction where in an appeal the chain of evidence is found to be not complete or the courts could reach to any another hypothesis other than the guilt of the accused, the accused person must be given the benefit of doubt which obviously would lead to his acquittal. Meaning thereby, when there is a missing link, a finding of guilt cannot be recorded. In other words, the onus on the prosecution is to produce such evidence which conclusively establishes the truth and the only truth with regard to guilt of an accused for the charges framed against him or her, and such evidence should establish a chain of events so complete as to not leave any reasonable ground for the conclusion consistent with the innocence of accused.
It was further held that a view to base a conviction on circumstantial evidence, the prosecution must establish all the pieces of incriminating circumstances by reliable and clinching evidence and the circumstances so proved must form such a chain of events as would permit no conclusion other than one of guilt of the accused. The circumstances cannot be on any other hypothesis. It is also well settled that suspicion, however grave it may be, cannot be a substitute for a proof and the courts shall take utmost precaution in finding an accused guilty only on the basis of the circumstantial evidence.
The last-seen theory, furthermore, comes into play where the time gap between the point of time when the accused and the deceased were last seen alive and the deceased is found dead is so small that possibility of any person other than the accused being the author of the crime becomes impossible. Even in such a case the courts should look for some corroboration.