Any missing link in the chain would destroy the entire prosecution case. In Hashim Qasim and another v. The State (2017 SCMR 986) the Apex Court ruled:

 “In cases of circumstantial evidence, there are chances of procuring and fabricating evidence. Therefore, Courts are required to take extra care and caution to narrowly examine such evidence with pure judicial approach to satisfy itself, about its intrinsic worth and reliability, also ensuring that no dishonesty was committed during the course of collecting such evidence by the Investigators …. circumstantial evidence may sometimes appear to be conclusive but it must always be narrowly examined, if only because this count of evidence may be fabricated in order to cast suspicion on another. Therefore, it is all the more necessary before drawing inference, if the accused’s guilt from circumstantial evidence to be sure and that there are no other co-existing circumstances, which weaken or destroy the inference then, in that case alone it may be relied upon otherwise, not at all.” 

Part Of Judgment
THE LAHORE HIGH COURT, MULTAN BENCH, MULTAN 
Criminal Appeal
13-09
2018 LHC 3164