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The problem of assessing the weight of circumstantial evidence linking a suspect with the perpetrator of a crime is considered. The quantitative measure PG of weight of circumstantial evidence that is used is the probability that culprit and suspect may be identified with certainty as one and the same based solely upon the circumstantial evidence. A unifying model for evaluating PG taking into account expert testimony is established on the basis of the Kullback-Leibler discrimination information measure. This model is applied to deriving PG based upon a jurist's interpretation of the expert testimony. An important property of the model is the first-order agreement, as the testimony becomes compelling, of PGs based on different jurists' viewpoints. The methodology developed is applied to the well-known Collins case.