the right kind of light
#1 in a series on Bitemark Evidence
If you have lived through a tornado in the Iowa countryside, you know what pitch-darkness means. You know the deep black of the storm cellar. No matter how long you stay down there, inside a cold hole in the lawn, your eyes do not adjust. You start to doubt what you hear and feel: your grandmother's breath on your neck, as she rocks you in her lap; your sister's whimpering cries; the funnel as it passes overhead.
But the thing is, there is no such thing as pitch darkness. In all darkness, there is light we cannot see. Light outside the visible spectrum.
If there is darkness, it resides somewhere else: inside our own eyes, our own bodies.
All of this occurs to me as I learn about bitemark evidence.
Imagine the darkness inside a bitemark or bruise: the darkness of the blood and ripped tissue, but also, the darkness of the person who clamped his jaw around a hand, a foot, a shoulder. And yet, the tooth marks and bruises appear dark not for lack of light, but because light penetrating the epidermis is being absorbed.
There is a light that actually emphasizes the dark, making an injury more visible and distinct: infrared.
Infrared light has a long wavelength. Long wavelengths travel deeper into the dermal layer, illuminating injuries in the lower skin layers - injuries our eyes cannot detect in normal light. Forensic scientists use infrared photography to reveal the bruises we otherwise would not see.
Which illuminates again the importance of process, how we need not just light, but the right kind of light, in order to see.