A three-judge bench comprising Justice G B Patnaik, Justice M Srinivasan and Justice S N Phukan, while acquitting two accused in a murder case, said ``when a case rests on circumstantial evidence, such evidence must be cogently and firmly established.

``These circumstances should form a chain pointing towards the guilt of the accused and the same should be so complete that there is no escape from the conclusion that within all human probability the crime was committed by the accused and none else,'' Justice Phukan said writing the judgement for the bench.

Sounding a word of caution, the bench said ``if any link in the chain is missing the guilt of the accused cannot be established.''

The case related to the murder of a taxi driver Balan in Kerala in March 1991. The accused allegedly hired the car andthen strangulated him after intoxicating him while proceeding from Koyilandy to Wynad.