Fingerprints and the Polaroid MP4 Copy Camera

 (Image found on the internet)

Polaroid MP4 Copy Camera

(Image found on the internet)

I recall when I was first interning as an Evidence Technician that I was tasked to take some photos of any fingerprints I found on some evidence I had just recently dusted for fingerprints. The camera that we used in the crime lab for this function was the Polaroid MP4 copy camera. This huge camera system was mounted to a copy stand which had incandescent lights positioned to eliminate as many reflections as possible.

The camera could take both standard Polaroid photos as well as take photos with large 4"x5" sheet film (large format film.) For this work, I was asked to take the shots with 4x5 film.

Being new at all of this work, I didn't know at the time what constituted a "good" fingerprint from a bad one. I was, after all, just a new intern. So every smudge I found, I photographed. I must have taken 50 or 60 shots. Well, after the film was developed, my supervisor called me over to tell me that not a single shot I took was worth taking! He explained to me that there were certain qualities in the fingerprints that needed to be there in order to make any kind of identification. Often in court, fingerprint examiners will be asked by the defense attorney, "How many points are needed to have an identification?" This is a difficult thing to answer, but in general, I'd say you'd need around 9 points to make a decent identification. But some experts can do it with less.

Back to my story... None of the prints I found on the evidence had a significant amount of points to make an ID. Most were just smudges. Totally worthless. I had basically wasted 50 to 60 sheets of 4"x5" film. That was expensive and time consuming! I felt awful!

But my supervisor said that everyone who comes through the lab makes this same mistake. In the hopes of catching a criminal, interns without any experience will document anything and everything. While it was a costly mistake to make, I learned an important lesson that day. Take photos of only the prints that had a chance to be identified. This meant that even though I was not a Fingerprint Examiner, I had to make the decision in the field as to which fingerprints found would actually get sent to the fingerprint examiner to examine!

From that point on, I made sure I learned more about what was considered a "good print" from a "bad one." You can find all sorts of "bad" prints on evidence. But it's always exciting when you find a good one and it get's identified. Yes, my work in the crime lab has sent criminals to prison. I did that even when I was just a lowly intern. By the way, it would be a terrific find to get a print on a piece of evidence that had the kind of ridge detail that you see in the image above. That would be an incredible find! Most likely you'd only get a small portion of a print and chances are it would not be as "clean" as you see it above. FYI: fingerprints are catagorized as "Whirls," "Loops," and "Arches." What kind of print would you call the one above?