Evidence

yes conviction will be taken on evidence who ever is present at the time of offence 

Circumstantial evidence is typically more reliable than direct evidence. Unfortunately, most people don't understand what circumstantial evidence is. Circumstantial evidence is evidence from which another fact can be inferred. For instance, DNA evidence is circumstantial evidence. If a person's DNA is found at the crime scene (more precisely, if DNA matching a person's DNA profile is found at the crime scene) then we can infer that the person (or someone with his identical DNA) was present at some point. Fingerprints are the same -- they tell us that someone touched something. We can then infer that the person with those prints must have been present, or must have held the weapon, or some other fact in controversy. Most scientific evidence is circumstantial.

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Suspicion expression is just a suspicion expression and not a Direct evidence, as such it is only a mere hearsay evidence. Being present at the place of crime does not mean he has seen the act of crime. Suspicion how ever grave can not take the place of proof.

I slightly differ with Ramachary sir, to my knowledge, the DNA,finger prints and scientifical evidences are substantive evidence which have higher value in the eye of law.  They cannot be said as circumstantial evidence. 

You put the word science and want to cover  every thing under it.

The basic concept of science is every thing is uncertain. Every thing is relative to each other is the theory of RELATIVITY on which modern day science is based.

So  science apart Mr CHARY has explained it in legal terms in very simple language..