FORENSIC SCIENCE
The Pennsylvania State University
Eberly College of Science
Whitmore Lab
University Park, PA 16802
Spring 2009
Fingerprinting Workshop II:
Non-Porous Surfaces - continued
Super Glue Fuming & Enhancement
Always wear a chemical respirator when working with chemicals
Background: Super Glue Fuming
You should have read the references concerning the history of Super Glue (SG) Fuming supplied or in your
text. It’s important to note that SG development of fingerprints has assumed an important, almost revered,
place in the crime scene investigation lexicon. Its importance is not just that it is a convenient way to develop
latent prints on nonporous surfaces but it also protects the prints by covering it under a polymer of
polycyanoacrylate polymer. Cyanoacrylate (CA) developed latent prints are off-white and must be developed
using powder dusting, RUVIS, or fluorescent staining. Their value as matching to known fingerprints is only
after development is:
1.
2.
3.
They protect the print from destruction during transit to the laboratory
Can be used as a first step in a sequential cascade.
They trap cellular, e.g., DNA, material that can be subsequently recovered.
Jurisdictions have varying procedures about whether CSI’s can enhance CA developed prints developed at the
scene. In this workshop, you will learn the basic methods, keeping in mind that a jurisdiction might require
that the CA developed prints be developed or enhanced at another location. This is not to say that the
chemical processing of the prints cannot be processed at the scene. They can but care and an understanding of
how the development process affects the surface the print is on.
Keep in mind that some items cannot be transported to the laboratory and must be developed, photographed
and/or enhanced at the scene. The CSI must decide the best way to develop the CA developed latent print.
There are several choices.
1.
Dusting with powder
a. This process can be repeated many times because the polycyanoacrylate is stable
b. Use black, dual or fluorescent powders - with or without magnetic.
2.
Stain with fluorescent dyes or use lanthanide chemistry to stain the lipids trapped by the SG
3.
Photographed using the RUVIS and then enhanced as above.
Recent work to understand how the SG fuming works has been published. It is clear that an initiation process
occurs as a nucleophilic attack. The chemicals that initiate are varied and typically attack the C=C moiety in
the cyanoacrylate molecule. Chemicals include, carboxylic acids - free fatty acids, amino acids, lactate and
possibly the pyruvate in fingerprints. Water trapped within the print emulsion is also a factor, whose role has
not been completely conclusively, but it is likely that the attack occurs from the water in sebaceous/eccrine
emulsion. Another possibility is that the water in the print emulsion offers an environment for other species to
initiate the attack. Other weak bases such as ethanol and methanol will also initiate the reaction.
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FORENSIC SCIENCE
The Pennsylvania State University
Eberly College of Science
Whitmore Lab
University Park, PA 16802
Exercise 1: Super Glue Fuming – Liquid Glue
Supplies/Reagents
Microscope slides
Basic Yellow 40
Black dusting powders
Fluorescent dusting powders
Rhodamine 6G
Ardrox
Methanol
Equipment
Adjustable heater
RUVIS
Respirator Masks, Goggles, Gloves & Lab Coats
Purpose of the This Workshop
1. To discuss appropriate safety procedures when using the glue fuming chamber
2. How to use the RUVIS for observing CA developed prints
3. How to stain CA developed prints
4. How to dust (and re-dust) CA developed prints
5. How to lift dusted CA developed prints
Procedure – work in groups of 2 or 3:
1. Wash your hands using soap and then dry your hands with alcohol – this is how to prepare
“Clean” eccrine prints.
2. Wait approximately 3 minutes then place a fingerprint 3 times (next to each other and
successively) on each of 3 microscope slides
a. Repeat using fresh 3 microscope slides using the same finger after wiping your
forehead and/or cheek.
3. Turn on the heat source in the fuming tent & allow it to come to temperature for several
minutes.
4. Place an Al tray containing water on another heat source and measure the humidity until it
comes to between 60-70%.
5. Place a fingerprint (after rubbing your forehead) on a black fingerprint lift card. Place the 6
microscope slides on a stand and the standard print into the fuming chamber
6. Fume the prints until the standard print on the lift card just begins to develop – do not over
develop.
7. Remove the fumed prints
Exercise 2: Fluorescent Staining Superglue Developed Prints
Procedure:
1. Place one of the clean print slides and one of the oily print slides in the BY 40 slide
holder and allow it to stain for 2 minutes.
a. Repeat with another slide by placing it into the Rhodamine 6G staining holder.
2. Remove the slides and wash them in running water in one of the sinks upstairs. NOTE:
be careful to keep the water from running directly on the stained prints
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FORENSIC SCIENCE
The Pennsylvania State University
Eberly College of Science
Whitmore Lab
University Park, PA 16802
3. Allow the prints to dry
4. Observe the prints in a darkened room using the ALS
Exercise 3: Dusting of Super Glue Developed Prints
Procedure
1. Dust the 3rd fumed microscope slide with black powder or magnetic fluorescent powder.
a. DO NOT OVERDUST the prints.
2. Lift the black powder dusted prints as you would any dusted fingerprint and transfer to a
white print lift card.
3. Observe the fluorescent prints using the ALS – 300-400nm
a. Before using the ALS, be certain to wear clear goggles
b. Lift the print using tape and transfer to a black pint lift card
Exercise 4: Vacuum Super Glue Fuming
Super glue fumes can also be obtained under a vacuum. The cyanoacrylate (CA) fumed prints obtained are
more translucent and are resistant to over development, which is unlike heat/humidity fumed prints.
Directions for using the vacuum system is posted with the apparatus.
1.
2.
3.
4.
5.
Put “Clean prints” onto microscope slides as described above.
Put oily prints onto clean microscope slides as described above
Following the directions next to the vacuum apparatus, fume the prints for 10-15 minutes.
Enhance the prints by dusting with black powder and by staining with Basic Yellow.
Compare these CA enhanced prints with those obtained using the heat/humidity method.
Exercise 5: Prints on Metallic Surfaces – Corrosion Analysis
There has been a lot of interest in developing prints on metallic surfaces, such as weapons, cartridge cases,
etc. Mostly, these techniques are not successful. Traditional techniques do not always work well. One
technique recently took advantage of the corrosive effect of the salts in fingerprints on the surface of metallic
objects. The success of this method depends on the metal and its reduction potential.
Procedure
1. Place a sebaceous fingerprint onto a piece of brass.
2. Hold the metal under a flame
3. When the fingerprint develops, the reaction is finished.
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FORENSIC SCIENCE
The Pennsylvania State University
Eberly College of Science
Whitmore Lab
University Park, PA 16802
Porous Surfaces
Background
Porous surfaces offer unique challenges to fingerprint examiners because the print diffuses into the matrix.
The components of the print remain the same, but the techniques used to develop them change. Typically and
historically, this process meant Iodine development of the oils followed by Ninhydrin development of the
amino acids and proteins in the prints. The problem with this approach is that the Iodine reaction is not
particularly sensitive and disappears rapidly over time, although it is useful for fuming sensitive documents.
Ninhydrin works well to develop prints but it too will deteriorate over time.
While Ninhydrin is a viable approach for fingerprint development, other techniques have gained in popularity,
as the chemical knowledge of the composition of fingerprints increased and other chemicals have shown
increased sensitivity. Researchers worked to increase the sensitivity of the Ninhydrin reaction, developing
Ninhydrin analogues, specifically ones having fluorescent properties. These newer chemicals have been
incorporated into a cascade development scheme that is better suited to finding prints on porous surfaces.
The first of these approaches was to combine Ninhydrin developed prints (Ruhemann’s Purple) with Zn or Cd
metal ions. At low temperatures, these complexes fluoresce. This is a treatment that follows Ninhydrin
development of prints, not before because the Zn or Cd reacts with Ruhemann’s Purple. Another chemical,
DFO, was found have increased sensitivity, meaning it located prints that Ninhydrin did not. Typically DFO
treatment occurs before Ninhydrin, so that following DFO with Ninydrin has become an accepted print
development procedure. Another chemical, 1,2-Indanedione, was found to react better and faster with amino
acids than DFO and hence can replace it as a development agent. In fact, it may obviated the need to use
Ninhydrin.
These chemicals however, do not develop the oils in porous substrates latent prints. The prints developed
sometimes appear spotty. In these instances, the spotty appearance is due to the development of pores on the
ridges where the secretions accumulate.
A typical cascade might include the following: Iodine, DFO or Indanedione, Ninhydrin, physical developer.
Iodine developed prints can be enhanced by adding starch followed by steam, which leads to dark blue-black
prints. Physical Developer is another technique where silver ions are reduced to metallic silver with the
resultant formation of dark prints.
Exercise 1: Iodine Fuming
Iodine vapors combine with the oils in fingerprints to give a non-permanent record of the prints of paper and
other substrates. The developed prints are not permanent and will disappear quickly. Once located, these
prints can be enhanced with Ninhydrin.
Procedure
1.
Place oily fingerprints on white paper.
2.
Follow the directions on the Iodine Fuming device to develop prints on the paper
3.
Dust the prints with powdered starch
4.
Use a steam iron (without acetic acid) to just moisten the prints. Observe the color that is formed.
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FORENSIC SCIENCE
The Pennsylvania State University
Eberly College of Science
Whitmore Lab
University Park, PA 16802
Exercise 2: Ninhydrin Developed fingerprints
In this exercise, you will learn to develop fingerprints on paper using Ninhydrin. Ninhydrin is a chemical that
combines with the amino acids and proteins in fingerprints in the presence of heat and humidity to form a
complex called Ruhemann’s Purple. Prints on paper will be dipped into a bath of 0.5% Ninhydrin in a solvent
(acetic acid, HFE7100, ethyl acetate, methanol). The paper is allowed to dry and then a steam iron is passed
over paper. The prints will develop as reddish-purple fingerprints.
Procedure
1.
Place fresh oily prints on white paper such that the prints cover 4 quadrants
2.
Cut the paper into quarters
a. Using a magnetic duster, dust one of the quarters with black magnetic powder – set aside
(1). Dip the solution into organic solvent (Ninhydrin solvent) & allow to dry
(2). Develop the dried paper with Ninhydrin as described below.
b. On another quarter, dip the paper into a solution of Ninhydrin & develop as described below –
(1). Set the paper aside for Super Glue Fuming.
(a). After fuming, dust the paper with black magnetic powder
c. To two other quarters, dip the solution into organic solvent
(1). Dust one with the magnetic black powder
(2). Super Glue Fume the other
3.
Be prepared to discuss the results.
Ninhydrin Development
1.
Dip the paper into a solution of Ninhydrin – completely saturate the paper
2.
Allow the paper to dry
3.
Place the paper onto a heated plate and allow the steam of an iron (containing dilute acetic acid) to
pass over the paper. Continue heating and steaming until all prints cease development.
4.
Alternatively,
Place the dried paper onto a flat surface and pass a hot steam iron over the paper until the prints
develop
Exercise 3: DFO Developed Prints
DFO will combine with the amino acids and proteins in fingerprints to produce a fluorescent print that is
visualized with the ALS.
Procedure
1.
Place prints onto a piece of white paper
2.
Spray with (or dip into) the paper a solution of DFO
3.
Allow the paper to dry
4.
Place the paper onto a hot plate for approximately 10-30 minutes – monitor the development of the
prints using the ALS.
5.
Photograph the developed prints.
6.
Follow this development with the Ninhydrin procedure described above.
7.
Photograph the Ninhydrin developed prints.
Exercise 4: 1,2-Indanedione Developed Prints
Indanedione will react with the amino acids and proteins in fingerprints to produce a fluorescent print that is
visualized with the ALS.
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FORENSIC SCIENCE
The Pennsylvania State University
Eberly College of Science
Whitmore Lab
University Park, PA 16802
1.
2.
3.
4.
5.
Place prints onto a piece of white paper
Spray the paper with the Indanedione solution in the fume hood & allow the paper to dry.
Place the paper onto a dry hot plate and cover the paper with a transparent plate.
Monitor the development of the fingerprints using an ALS @ 535nm – the hand-held ALS works well
for this purpose (use the AC instead of the battery).
Follow this development with Ninhydrin.
Exercise 5: Heat Developed Prints
A recent publication described a method for developing prints on porous and presumably on other surfaces
after heating the prints at approximately 300 deg C for 10-20 seconds. After 10 seconds the prints show
fluorescence using a wavelength of about 505nm and visualized using a 450nm filter. On further heating, the
print begins to turn dark and is visible.
Procedure
1. Place prints onto white paper
2. Place the paper into an oven @ 300 deg C.
3. After 20 seconds, remove the paper and view the prints that have developed.
Exercise 6: Lanthanide Developed Prints
Many lanthanide elements form fluorescent coordination complexes. Europium has been used to develop
fluorescent prints on both porous and non-porous surfaces using a procedure much like SPR. The surface is
sprayed carefully with reagent 1 and then allowed to dry. Once dry, the surface is sprayed again with reagent
2 and again allowed to dry. The developed prints are visualized under UV light. If there is significant
background, the surface can be washed with water, which can quench the background fluorescence.
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