This is a study that Paul Nelson did on underwater fingerprints during his masters program in forensic science at George Washington University in Washington DC. Paul is a great friend and became a great UCI diver. I thought he was being funny when I saw on his UCI application rocket scientist as his occupation. Then I met him and found out he worked for NASA as a... rocket scientist. His findings are put here with his permission.
Water comprises approximately ninety-nine percent of the secretions that make up fingerprints, with various minerals, fats, acids, salts and oils the remainder. The first component of the prints to leave is the water, through evaporation and/or absorption. When deposited on surfaces, these prints can be detected and enhanced days later. Eventually, the oils and organic components also will break down, making lifting of the prints impossible, even if they can be detected.
Most fingerprint powders react by clinging to the water and fatty deposits, highlighting the ridge detail. But even without the water, fingerprints are still quite viable. Therefore the water is not essential for prints to be detected, enhanced, photographed and lifted.
Having heard stories of latent fingerprints being detected on items recovered underwater, the author decided to test the veracity of these anecdotal reports. A series of experiments were devised to look for fingerprints on items submerged in water then taken from the water on sequential days, and also to test two different methods of enhancing any prints detected.
II. Experimental Methods
For the immersion media, several large tubs of water were collected from the Potomac River, at the Theodore Roosevelt Island Park in Arlington, Virginia. Initially, the experiment was to be performed on pieces of angled aluminum cut into two-inch sections, cleaned with alcohol swabs, allowed to dry, printed on the outside faces, then set into the tubs of water. The inside faces acted as negative controls. There were to be three pieces of aluminum removed each day. Each piece was to have one face subjected to a simple powdering, and then each piece was subjected to cyanoacrylate "super glue" fuming. After the aluminum had been put into the water, the tubs were transported to the laboratory. Finally, a positive control would be printed and tested for each method, for each day.
The day after the aluminum was immersed, the author decided to test an additional substance as a print surface. Glass slides were cleaned with alcohol swabs, allowed to dry, printed twice on one side then dropped into the tubs of water as well. Again, three slides would be tested each day.
After the initial experiments had been run for almost one week, a final experiment began. Using the same method of cleaning and printing, spent pistol cartridges were immersed in the water. Three cartridges were to be tested each day for prints on either side of each shell.
For the pieces of aluminum, the results were inconsistent. On some days, more than one print was detected while on other days no prints were detected. As an example, initially no prints were detected on the third day of immersion, but two were detected on day four. Suspecting that transport of the tubs of water might have caused the pieces of aluminum to rub against one another, thereby wiping some of the prints off, the author printed and dropped in the last pieces of aluminum on hand and left them relatively undisturbed for three days. When drawn from the water, prints were found on all pieces, using both methods. Some prints had less detail or were fainter than others. Regardless, prints were detected and enhanced, shown in Figure 1.
Fig. 1, Prints detected/enhanced, 3 days immersion, black powder and cyanoacrylate
Figure 2 is a close-up of one print from the same batch.
Fig. 2, Close-up of print detected/enhance, 3 days immersion, cyanoacrylate
All the glass slides for each day had both prints on them, and both detection methods worked well, though as the days wore on, the quality of the prints did degrade to a degree. The slides were all immersed after the tubs of water had been transported to the lab, so they did not suffer the effects of transport. Figure 3 is of slides that were immersed for six days, with black magnetic powder used on one print. Figure 4 is of the same slides after they had also been "fumed" and powdered.
Fig. 3, Prints detected/enhanced, 6 days immersion, black powder, one print only
Fig. 4, Prints detected/enhanced, 6 days immersion,black powder and cyanoacrylate
The fired pistol cartridges also retained partial prints that could be detected and enhanced using both methods through the four days of their testing. Photography of the cartridges did not produce any decent images of the enhanced prints, though the shells are available for examination. As opposed to the aluminum and the glass slides, the simple powdering produced a more clearly visualized print than the "super glue" fuming followed by powdering.
The table below summarizes the results of the experiment. It lists the number of prints detected out of a possible three for each type of item, and each method of testing. Day 3 has the results of two batches of aluminum, the initial group, and the second group subjected to less stress.
Number of Latent Prints Detected & Enhanced
This was a carefully designed experiment that clearly could not reproduce the true effects on an item that had been thrown into a river, lake or ocean and left for several days. If someone were trying to destroy or hide evidence, it probably would not have been handled carefully to ensure the fingerprints were intact during submersion. Currents, bottom mud and other factors could very easily cause prints to fade faster. Indeed, the author suspects a "real world" effect to be the cause of results for aluminum to be inconsistent with the results for glass slides and brass pistol cartridges.
However, the basic principle of detection of prints after several days of immersion in
water is sound. Standard procedure for almost any piece of evidence recovered is to test it for latent prints. Any piece of evidence recovered from underwater should also be tested for prints, no matter the amount of time spent beneath the surface.
Finally, it would be prudent if a more thorough study, using more "realistic" conditions, greater times spent underwater, more types of surfaces and more methods of detection and enhancement, were performed.
The author wishes express his gratitude and appreciation to the George Washington University Forensic Sciences Laboratory Assistants, Amy Balle, Kristin Meyer and John Witkowski, for all their assistance in performing this experiment.
The author also owes a great debt to Dr. Lisa Christine Turtzo (M.D, Ph.D.) for her help in the planning of the experiment. Without her guidance, the experiment probably would not have had the proper controls and redundancies.