A first assessment of the reliability of an improved scent identification line-up

To properly evaluate different forensic techniques, it is important to know how reliable these different techniques are. The reliability of scent identification line-ups is unknown. The purpose of this study was to describe, and employ, a reliability testing method for scent identifications using trained police dogs and a novel scent identification procedure. Two kinds of experiments were prepared: suspect = perpetrator experiments, and suspect not equal to perpetrator experiments. Six dog/handler teams participated in 10 experiments, five of each kind. The reliability of an identification, or the diagnostic ratio, is the percentage correct identification in suspect = perpetrator experiments divided by the percentage false identification of the suspect in suspect not equal to perpetrator experiments. Factors that influence the reliability of scent identifications are discussed, and the results of the scent identifications are compared with recent reliability estimates of other forensic techniques.