The success of forensic identification largely depends on the availability of strong evidence or traces that substantiate the prosecution hypothesis that a certain person is guilty of crime. In light of this, extracting subtle evidences which the criminals leave behind at the crime scene will be of valuable help to investigators. We propose a novel method of using strain pattern extracted from changing facial expressions in video as an auxiliary evidence for person identification. The strength of strain evidence is analyzed based on the increase in likelihood ratio it provides in a suspect population. Results show that strain pattern can be used as a supplementary biometric evidence in adverse operational conditions such as shadow lighting and face camouflage where pure intensity-based face recognition algorithms will fail.