The use of black and white infrared photography for recording blunt force injury

Infrared (IR) wavelengths penetrate skin and can selectively image volumes of subsurface blood. Twenty-eight blunt force injuries on nine decedents were photographed with color and IR film to compare the ability of each to image the injury. Of the 28 injuries, 10 were clinically interpreted as contusions, 4 as abrasions, 10 as abraded contusions, and 4 as erythematous discolorations, nos. Twenty-four of these injuries were incised to determine the presence and extent of subsurface bleeding. It was found that contusion had been clinically missed in five cases, three because they were hidden by abrasion and two because they appeared only as a mild cutaneous erythema. All five cases were detected by IR and verified by incision. Melanin pigmentation contributed to masking of contusion in one case and postmortem lividity confounded interpretation of contusion in one case. In all 14 injuries featuring abrasion as a component, IR de-emphasized or eliminated the visibility of abrasion. A single false negative was reported in which a visible contusion, verified by incision, was not seen with IR. In comparing injury patterns, color and IR renditions were dissimilar in a number of cases reflecting the difference between the manner in which light and IR photography imaged the depth and volume of blood within an injury. In summary, IR imaging of wounds can discover hidden bruises, verify clinical diagnosis of bruises, and augment interpretation of wound patterns.