The use of infrared aided photography in identification of sites of bruises after evidence of the bruise is absent to the naked eye.

The purpose of the study was to determine whether Infrared imaging could play a role in the detection of previous blunt force injury after resolution of skin changes were no longer visible to the human eye. Investigations were performed using an adapted digital camera and the same standard Nikon camera body to photograph the bruises of ten volunteer adult subjects. The same lens was fitted to each camera body and each bruise was photographed until it was no longer possible to identify it with the naked eye. The results of photographing subjects over 6 months demonstrated that the median time the bruises persisted in both groups was approximately between 18 and 19 days. There was no statistically significant difference between groups of bruises photographed with both the infrared digital camera that had been adapted to capture only infrared light, and with the standard camera which had the same lens fitted to it. The two groups of photographs of bruises imaged at the same time with the two cameras were not significantly different with regard to what skin changes could be detected. The use of the near infrared spectrum, with wavelengths that are longer than the human eye can detect, did not reveal significant evidence of bruising after it had faded from view to both the human eye and to a standard camera.