Author: M.J.M. (Theo) Velders (retired), Politie Brabant
Zuid-Oost, Eindhoven, the Netherlands
At a crime scene, we regularly find latex or vinyl gloves which have been left behind by the perpetrators. As crime scene officers, we are then confronted with the question of what to do with these gloves. We know these used gloves can contain fingerprints but how to make them visible?
In most cases such gloves are secured only for DNA investigation. Sometimes there are attempts to make prints visible, usually with chemical methods, but as most of us probably have experienced, the results of chemical methods are usually not very satisfying.
Usually perspiration and the powder in these gloves are blamed for having destroyed the latent fingerprints.
Up until 2001, I succeeded only once in my 30 years as a crime scene officer to visualize a fingerprint in a latex glove. I had tried many times to treat disposable latex and vinyl gloves with chemical means, but virtually all these attempts failed to produce a result.
Then in the middle of 2001, a collegue handed me four latex gloves which had been thrown away by burglars when leaving a crime scene. As so often before, I started working on the gloves, treating two of them with ninhydrin and the others with cyanoacrylate fuming. Unfortunately, both methods failed to visualize any prints.
After this disappointment, I wondered if it might be possible
to get any fingerprints off of these gloves using a black gelatin lifter.
To my amazement, a number of excellent prints were lifted from these chemically treated gloves. I had a strong suspicion that this could be a real breakthrough.
Looking for a solution
Were these results with the four latex gloves a coincidence,
or could it be that lifting prints with a Gellifter was the solution to a big
Researching the internet, I found that collegues around the world have used the following methods:
These methods gave varying results (see references).
Determining the inside of a glove
To research adequately, we needed first to nail down a few things. For example: what is the inside and what is the outside of a latex or vinyl disposable glove? How do you tell?
Some people argue that the outside is always dirtier than the inside. Others assume that when a person pulls off these gloves, the inside automatically ends up on the outside. But what if the wearer of the gloves had dirty hands before he put on the gloves? Or if the sweat of the hands discolored the latex?
Another question is: what is a left glove and what is a right glove? This last question cannot be answered by just looking at used gloves. However, we can determine with certainty the inside and the outside, provided the gloves have been worn only once.
Carefully inspecting different brands of gloves showed that the cuff of the gloves is always manufactured in the same way. By inspecting the rolled bead cuff, or incising it in case of doubt, it is easy to see which side is which. With an unused latex or vinyl glove, the bead is always rolled to the inside (see picture 1). Cutting through the bead reveals a spiral that shows how it was rolled.
Having established this, we proceeded with comparative examination in three phases.
Test 1 - Ninhydrin: Treating finger marks on a
powdered latex glove showed hardly any development of ridge detail. The latex,
however, was discolored by the ninhydrin (picture 3).
Test 1 - Lifting: After ninhydrin treatment, the test
marks were lifted 6 times with a black gelatin lifter. The marks achieves their
best at the sixth lift (see picture 4).
Test 2 - CA and Rhodamine 6G: Powdered latex gloves
were fumed with cyanoacrylate first and then treated with Rhodamine 6G solution.
The marks did not fluoresce, but the surface of the latex glove did (see picture
Test 4 - No chemical treatment; only lifter was used.
Pictures 9 and 10 show the difference between the first and fifth lift with a
Test 5 - CA and Rhodamine 6G: Powder-free latex gloves
were treated with cyanoacrylate and Rhodamine 6G, as in test 2. The developed
prints were of low quality (see picture 11).
Test 7 - No chemical treatment: The test prints on
powdered vinyl gloves were processed only with the Gellifters. Remarkably, the
color of the ridges changed from dark to light on subsequent lifts (picture 15
Test 8 - Gentian Violet Staining: A powdered latex
glove was worn for 15 minutes and after 48 hours was treated with gentian
violet. After rigorous rinsing with water, the gloves were left to dry
Conclusions from test phase A
Ninhydrin, suitable for porous materials like paper
and wood, is not suitable for developing prints on latex and vinyl disposable
Gentian violet stains not only fingerprints but also
latex, which leads to a loss of contrast.
Iodine did not reveal any ridge detail, but did discolor the latex and vinyl gloves.
The best results on the latex and vinyl gloves were obtained with gloves that, with no previous chemical treatment, were processed with black Gellifters.
This second phase of the test came close to the conditions found in case work. The gloves (powdered latex gloves) were actually worn during work, and the search for latents was not started sooner than 6 days later. Because of the results from phase A, it was decided to not use chemical methods in Phase B, but only lifting with black Gellifters.
Nine different persons took part in this phase of the
research. From the 9 pairs of gloves, 90 fingers where rolled, and 59 of the 90
fingers yielded identifiable prints. From each glove one or more identifiable
prints were recovered. In total, a 65% score was obtained.
A number of lifted prints obtained from this phase of the investigation are depicted in pictures 19-26.
examples from phase B
This part of the research involved twelve powdered latex
gloves that were secured from a hemp nursery after a raid in which no suspects
After all gloves were separated, the fingers were rolled on
strips made out of black BVDA Gellifters.
Pictures 28-31 show some results:
Because we cannot tell whether a glove has been worn on the left or right hand, we cannot lift only an area where ridge detail is expected. The fingers have therefore to be rolled 360 degrees, in a continuous movement, till at least 8 revolutions have been made. In most cases 3-6 revolutions were optimal. One can of course choose the best print for photography.
In this research, lengths of PVC tubing of different
diameters was used to fill out the fingers of the gloves. The cylindrical shape
of such tubes is not optimal, since the glove fingers are more or less conical
A. A properly sized fill out piece is inserted into the finger of a latex glove
B. The fill out piece is screwed onto the roller
C. The other parts of the glove are protected by a polyethylene sheath
|D. The other parts of the glove are additionally protected by an aluminium case.|
E. The roller in action, fill out parts for differently sized fingers are depicted in the background.
After the post on CLPEX.com, Ian Rudden responded to a post I made regarding additional cases where this technique had been used in casework:
Lifting Latent Prints Directly from Inside Latex Gloves
Ian Rudden, Criminal Record Centre, KwaZulu Natal, South Africa
After reading the article “Visualization Of Latent Fingerprints On Used Vinyl And Latex Gloves using Gellifters” authored by Theo Velders I was immediately intrigued and, I must admit, slightly skeptical. Other methods that my colleagues and I have had very limited success on this type of substrate. The article concerned the lifting of latent prints from the inside of latex gloves using only gel lifters, a cylindrical shaft, oblique lighting and no other enhancement methods. After reading the article, I slipped on a glove for a while and proceeded to experiment straight away. I couldn't believe the results, so I repeated the experiment with the same result: the initial trials provided a 100% success rate!
After the initial trails, in which there was almost no time delay between the removal of the glove and the examination of the glove, I began more structured experimentation and research using different types of latex gloves e.g. powdered and powder free as well as different makes of glove.
The gloves were worn for periods varying from 15 minutes to just under an hour. Once removed the gloves were examined at different time intervals (a different finger at each interval). The method I employed to examine the glove was to cut one finger off at a time.
The gloves that were worn for the experiment by me and a volunteer were examined at intervals varying between 30 minutes and 9 days. After 9 days I was still achieving positive results. I was also able to lift an identifiable print (in South African terms, at least seven ridge features) from a glove used in an armed robbery. The glove was examined 15 days after it was recovered in the getaway vehicle.
Using only gel lifters, the “suspect” glove and a cylindrical shaft I was able to roll the finger on to a strip of gel lift. Once rolled the gel lifter was examined using oblique lighting (the print is generally not visible at all until examined with a light). I found that white or green lights gave the best results. As with the research in the Theo Velders article the best results were only achieved after several 360° revolutions, sometimes as many as 15.
The gel lifter that is used in South Africa is manufactured locally by the logtec section of my unit. I suspect the composition is very similar to that manufactured by BVDA. The lifter that I used is distributed with a cellophane cover that is removed and replaced when prints are lifted under normal circumstances, I however found that replacing the cellophane when using this method destroyed or adversely affected the quality of the print.
During the course of these experiments I found that powdered gloves produced poor results (almost always negative) under lab conditions. However the glove I examined that had been used during the armed robbery was a powdered glove and as mentioned produced a positive result after 15 days.
The overall positive rate (identifiable prints) that was achieved for this series of experiments was over 60%.
The findings and results of my research project are currently being disseminated throughout my province and have impressed some of the more experienced and seasoned experts I work with.
Remember, the message board is always open: (http://www.clpex.com/phpBB/viewforum.php?f=2). For more formal latent print discussions, visit onin.com: (http://www.onin.com)
UPDATES ON CLPEX.com
Updated changed links and deleted broken links to news articles.
Feel free to pass The Detail along to other examiners. This is a free newsletter FOR latent print examiners, BY latent print examiners. There are no copyrights on The Detail, and the website is open for all to visit.
If you have not yet signed up to receive the Weekly Detail in YOUR e-mail inbox, go ahead and join the list now so you don't miss out! (To join this free e-mail newsletter, send a blank e-mail to: email@example.com) Members may unsubscribe at any time. If you have difficulties with the sign-up process or have been inadvertently removed from the list, e-mail me personally at firstname.lastname@example.org and I will try to work things out.
Until next Monday morning, don't work too hard or too little.
Have a GREAT week!