Ultraviolet Radiation and Forensics

In forensics, ultraviolet radiation is used to enhance injuries of the skin. It has been reported that ultraviolet radiation can help visualize an old bruise and can also estimate the shape of the object that caused the bruise. For example, where bruising was faint, old and difficult to recognize, ultraviolet radiation was used to successfully identify bite marks 6 months after an injury. However, long-term exposure to ultraviolet waves is known to adversely affect the skin and eyes. Therefore, although ultraviolet imaging is useful for documenting injuries related to violence, it is not recommended for use in normal children.

If not Ultraviolet Radiation, then what?

In one study, 15 bruises in healthy volunteer children (average age 7-13 years) were examined. These children acquired the bruises in typical daily accidents such as accidents while exercising, play or falling down the stairs. In a dark room, each of the bruises were observed and photographed under visible light. Then the bruises were illuminated and photographed using four additional forensic light sources: blue ring, blue, violet and ultraviolet. To measure chronological changes, these same observations and photography were also performed daily for the first seven days, then weekly until the bruises could no longer be observed. The conclusion of the study determined that bruises in children can be observed for a longer duration using violet light compared to visible, blue ring or blue ultraviolet.  (Mimasaka, Oshima, & Ohtani, 2018)

What does this have to do with criminal cases?

At this time, there is still no means of dating the bruises using this method, but the ability to observe bruises in children for a longer duration allows investigators to document bruising even when the reporting timeframe has been delayed. Attorneys involved in cases where violet light has been used should be familiar with the benefits and limitations of this technique.


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