DV Tip of the Week

5 MIN READ

A hammer is a great tool for putting nails into wood. It's not a great tool for tightening nuts.

Alternate light source has had great success helping to identify possible signs of semen or urine. Urine and semen both glow under ultraviolet light. Samples of the targeted area can be obtained and then a determination made as to whether the suspected sample is what was suspected.

Alternate light source technology is being used by forensic nurses and law enforcement in domestic violence situations for help with injury identification. Its use in this manner is the part of great scientific controversy.

The (very) basics of how ALS works.

Remember the spectrum of light from science class? (Red, orange, yellow, blue, green, indigo, violet)

When you shine an alternate light source on an object, it will either absorb the light, reflect the light, or fluoresce. Most of us have seen the fluorescence on a black light poster before. Using various bands of light, you receive various responses.

So what's the big controversy?

Let's look at three scenarios. In one, you will find no controversy. In the second, a possible controversy, in the third, big controversy.

The barely visible injury enhanced

Let's say you are examining a victim and see what appears to be a 3 centimeter bruise on their arm where they say they were grabbed. You see this without the aid of any device in normal lighting. You try to photograph it, and the photo either doesn't depict the injury or doesn't clearly depict the injury.

Now you apply an alternate light source light to the area and using special glasses, you can see the light absorption of the 3 centimeter injury and with proper adjustment to your camera, you capture that image.

You have enhanced the image. Such image enhancement, as opposed to image manipulation has long been supported in the law.

No problem.

The barely visible injury enhanced part 2

Let's say you are examining a victim and see what appears to be a 3 centimeter bruise on their arm where they say they were grabbed. You see this without the aid of any device in normal lighting. You try to photograph it, and the photo either doesn't depict the injury or doesn't clearly depict the injury.

Now you apply an alternate light source light to the area and using special glasses, you can not only the 3 centimeter image, but the light is absorbed in an area of 5cm. There still is no issue saying your enhanced image is that of a 3 centimeter bruise. Your 3 centimeter injury now appears to be a 5 centimeter injury. Or is it?

Now we are getting into a controversial area. According to a number of medical professionals from emergency physicians to forensic nurses, ALS cannot be used to diagnose injury. Saying you have a 5cm bruise would be diagnosing the additional area as a bruise. You have gone beyond enhancement.

The invisible injury

Let's say you are examining a victim and you see nothing on their arm where they say they were grabbed. This is without the aid of any device in normal lighting. You photograph the area, and the photo either doesn't show anything..

Now you apply an alternate light source light to the area and using special glasses, you see light is absorbed in an area of 3 centimeters. Your invisible area now appears to be a 3 centimeter area of absorption. What is this? About the best you can say is that it is an area of absorption. If you can't diagnose with it, what can you say?

This is where we have the most controversy. Depending on your jurisdiction, the introduction of such evidence is governed by either the Kelly, Frye, Reid, Daubert, or some combination of these standards. The issue becomes that there is no agreement in the scientific community about the validity of such tests.

I found no citable, published opinions on the use of ALS for this purpose. Published research and forensic organizations warn against its use as a diagnostic tool.

What about calling it an area of absorption?

What would the relevance be unless its use is scientifically validated? It would be the same as saying a defendant failed a polygraph.

Does ALS have any value?

Absolutely! It can be used to enhance an injury that you see with the unaided eye so it can be better photographed. I suggest one image of the area without ALS, then additional images with varying spectrums of light.

If you see more than the area of light reflected than your original area, be very cautious about calling the larger area additional injury.

If you cannot see an injury with the unaided eye in an area where the victim complains of pain, document the area of pain. Image it. Image it again with ALS. Have victim re-examined if at all possible within 24, 48, 72, 96 hours to see if bruising becomes visible to the unaided eye.

Until ALS becomes validated in your jurisdiction under the appropriate standard, do not use it as a form of diagnosis.

Want to learn more about this?

Email me: gfineman@dvtrainandconsult.com with any questions.

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