Breaking NEWz you can UzE...
compiled by Jon Stimac
Real-Life 'CSI' Isnt Sexy
- Feb 27, 2007 ...the reality of crime-scene investigation
is often more gross than sexy...
Police 'did not follow protocol'
INDEPENDENT ONLINE, So AFRICA
- Mar 2,
2007 ...a senior police officer has admitted to incorrectly
handling certain exhibits found at the scene of the Lotz murder...
Fingerprint 'not faked'
NEWS24, So AFRICA
- Feb 26,
2007 ...there was a clear fingerprint on a
DVD cover found on the scene of the murder says Officer...
Finger on Solving Crime
- Feb 24, 2007
...local fingerprint examiners among elite in their field...
Recent CLPEX Posting Activity
containing new posts
Moderated by Steve Everist and Pat Wertheim
Idea on blind verification
Becky Mon Mar 05, 2007 1:55 am
Endless postings about the McKie case...
Dick Dastardly Sun Mar 04, 2007 11:19 pm
What does the McKie case mean ?
Dr. Dror Sun Mar 04, 2007 10:26 pm
More Thoughts On Bias
Charles Parker Sun Mar 04, 2007 12:16 am
Cherrill of the Yard
EmmaC Sat Mar 03, 2007 10:09 am
Level 1 and 2 Detail
Charles Parker Fri Mar 02, 2007 6:54 am
Percentage of Latents left at scenes
Macgyver130 Fri Mar 02, 2007 12:17 am
pressure distortion and its effects on an AFIS match
kris33 Fri Mar 02, 2007 12:14 am
Thank GOD for stupid crooks!
Cindy Rennie Tue Feb 27, 2007 12:18 pm
Latent print evaluation and comparison "bench notes&quo
skflynn Tue Feb 27, 2007 6:07 am
Who tested the testers?
Daktari Tue Feb 27, 2007 12:35 am
Justice 1 Reports
Daktari Mon Feb 26, 2007 11:20 pm
Mike Fletcher Mon Feb 26, 2007 8:14 am
UPDATES ON CLPEX.com
updates on the website this week.
we looked at a
review on MXRF related to latent print examination.
we start a series on U.S.
patents related to latent print examination. What better way to get a
look at what's around the corner than to look at patent filings and recent
awards. Over the next few weeks we will take a look at some of today's
ideas that may become the realities of tomorrow.
Latent Print Development on
Porous Surfaces through Solid Chemical Sublimation
new patent application by Doug Arndt,
 This application claims priority based on U.S. Provisional Patent
Application Ser. No. 60/702,840, filed Jul. 27, 2006, entitled METHOD OF
DEVELOPING LATENT FINGERPRINTS. The contents of said provisional application
are incorporated herein by reference.
FIELD OF THE INVENTION
 The present invention relates to the development of latent
BACKGROUND OF THE INVENTION
 The term "chemical developer" as used in the forensic fingerprint art
refers to the visualization of the components or constituents, e.g., oils,
salts, amino acids deposited by the ridge pattern of a person's fingertip,
i.e., fingerprint area, onto a porous substrate such as paper. It is to be
noted that the term "fingerprint" or "fingerprint area" as used herein
includes palm as well as foot prints.
 Several methods have been used to develop latent fingerprints
particularly on porous substrates such as paper. One method, described in my
U.S. Pat. No. 6,841,188 ("'188 patent"), involves the preparation of a
reagent solution, i.e., 8-hydroxyquinoline or derivative by mixing it with a
complexing agent such as a metal salt and applying the solution, e.g., by
spraying, dipping etc. to a porous substrate wherein the solution is
adsorbed and precipates onto the substrate surface allowing the precipate to
highlight the latent image.
 While this method has achieved considerable success it has certain
disadvantages including (a) to some extent shelf life limitations, (b)
possible staining or blackening of the underlying documents, (c) possible
destruction of the latent print residues and (d) the requirement that the
substrate be porous.
 The '188 patent discusses another prior art latent print developing
method which involves the reduction of a silver salt in solution to
elemental silver which precipates and adsorbs onto the surface of the latent
print. The disadvantages of this method are also discussed in the '188
 Iodine and ruthenium tetroxide have also been used in a fuming
process as well as vacuum sublimation of relatively high vapor pressure
chemicals and dyes. Butane torch systems have been used to vaporize
cynoacrylates and dyes. Ninhydrin and DFO solutions have also been used to
develop latent prints. However, such solutions require that the materials be
mixed and weighed. In addition, such solutions are generally flammable,
provide inhalation hazards, often cause inks to run, and they can take
several hours to weeks to develop prints. One company markets a refrigerant
to which the ninhydrin or DFO can be added to overcome many of the problems,
but it is quite expensive.
 Inkless systems have been developed to enable a user to take the
fingerprints of an individual while present as contrasted with the
development of a latent fingerprint. Such inkless systems rely on the
reaction of two chemical reagents at the time of fingerprint development.
Typically a nonstaining first reagent (color former) such as a transition
metal salt is applied to a person's fingertips and a second reagent
(developer), such as 8-hydroxyquinoline or it's derivative, is pre-applied
to or inherent in the recording medium such as paper. The reagents remain
isolated until the fingerprint is taken. See, for example, U.S. Pat. Nos.
4,029,012; 4,182,261 and 4,262,623 ("'623 patent"). More recently the use of
a chealting agent has allowed the two reagents in solution to be located in
the same container by preventing the reagents from chemically reacting until
exposed to the moisture from the skin and/or the recording medium. See U.S.
Pat. No. 6,488,750.
 The assignee of the present application and it's predecessor, one of
the early pioneers in inkless/nonstaining fingerprint systems, introduced an
apparatus in the late 1970's called the "Digit 10.RTM." which is described n
the '623 patent. The Digit 10.RTM. apparatus had (and as marketed today has)
a reagent dispensing pad containing a color former in the form of a
transition metal salt, i.e., FeCl.sub.3 in one area and a development
chamber containing a developer in the form of 8-hydroxyquinoline affixed to
an open celled fibrous pad in an adjacent area. Prior to the fingerprinting
procedure a paper sheet or card, preferably meeting FBI specifications, is
placed in the development chamber and the finger tips, of the person to be
fingerprinted, are pressed against the color former dispensing pad to coat
the ridge patterns and then the fingertips are pressed against the sheet or
card. The development chamber is then closed allowing the gaseous phase of
8-hydroxyquinoline to penetrate the paper and react with the FeCl.sub.3 with
the reaction product emulating the ridge patterns of the person's
fingertips' ridges. The '623 patent points out that the developer chamber
can be heated, e.g., to increase the sublimation rate of the developing
solution. The Digit 10.RTM. apparatus provides outstanding black prints,
which as required by the FBI, have an expectant 30 year lifetime.
 Obviously one cannot apply a color former to the fingertips of a
non-present person. I have discovered that a latent fingerprint may be
quickly developed through a dry method, eliminating the need for a separate
color former reagent such as FeCl.sub.3 of the Digit 10.RTM. system while
obviating the application of liquid reagents via the '188 patent system and
the lengthy development time as well as the need for bulky heat sources,
fuming and vacuum chambers, ventilation systems and personnel protective
equipment associated with one or more of the above prior art processes. The
resulting images on the substrate need not have a long life expectancy since
such images may be converted to a more permanent storage medium if desired.
SUMMARY OF THE INVENTION
 A method of developing latent fingerprints on a porous, e.g., paper,
or nonporous, e.g., plastic, substrate in accordance with the present
invention comprises a) providing a solid chemical (developer) compound
capable of sublimating sufficient quantities within a temperature range of
about 72.degree. F. and 450.degree. F. for a short time interval so that the
sublimated gaseous phase of the compound is capable of reacting with one or
more of the constituents found in the residues of a latent fingerprint to
form a discernable image of the fingerprint in the visible spectrum with or
without exposure to external radiation and b) exposing the substrate to the
chemical compound within said temperature range and for at least said short
time interval to develop the image.
 The later step is preferably carried out through the use of an
apparatus having a development compartment with the chemical compound in
gaseous communication with the compartment and means for releasably opening
and closing the development compartment so that the substrate may be placed
in the development compartment when open and the sublimated compound
preferably may be inhibited from egressing the compartment when closed.
 The substrate possessing the anticipated latent fingerprint is placed
within the open development compartment which is then closed for a selected
time and the compartment preferably heated to allow the sublimated chemical
to react with the print residue to develop the print. The compartment is
then opened and the substrate removed.
 The residue constituents of latent fingerprints, of primary interest,
are oils, salts and amino acids. The developer compound in a sublimated
state must be capable of reacting with one or more of such constituents
within a reasonably short time interval to provide either a visible image
without the need for external radiation or with such radiation. Preferably
the developer compound is chosen to provide fluorescence under suitable
external radiation. Such external radiation may be chosen to substantially
eliminate interfering background or noise fluorescence as is well known in
 The developer compounds that are best suited for the invention must
be low-energy solids with molecular attractions (e.g., van der Waals force)
keeping the solids together but which attraction is easily overcome by the
application of heat.
 I have found that the following developer compounds react with the
listed latent fingerprint constituents at a reasonably low temperature,
e.g., 72.degree. F. to 450.degree. F. and generally between about
100.degree. F. to 300.degree. F. to provide a discernable and satisfactory
image of a latent fingerprint:
 Amino Acids: Aldehydes, ketones, quinones (e.g. benzo-, naphtho-,
anthra-), 4-(dimethylamino)cinnamaldehyde, quinolines, and dansylated
 Salts: 8-hydroxyquinolines, acridine hydrochlorides
 Oils: lipophylic compounds in general, and specific ones such as
acridines, coumarins such as those typically used as laser dyes, low
molecular weight azoles (nitrogen containing with oxygen substitution are
oxazoles and nitrogen containing with sulfur substitution are thiazoles),
liposomes (e.g. Nile Red), stilbenes, azos, azolines, and conjugated
polycyclic aromatic compounds containing at least three fused rings that
include without limitation anthracene, benzanthracene, pentacene,
substituted pentacene, naphthacene, phenacene, substituted phenacene, and
 Other dry developer compounds, which have been found to develop
latent prints with varying degrees of effectiveness, are set forth in the
following discussion of the preferred embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIGS. 1, 3a and 3b are perspective views of an apparatus suitable for
use in carrying out the method of the present invention with FIG. 1 showing
the hinged cover in an open position exposing the heating element in the
base and FIGS. 3a and 3b showing the pad carrying the chemical developer
compound and the foam cushion in place on the base and cover, respectively;
 FIG. 2 is a block diagram of a power supply for the heating element;
 FIGS. 4a and 4b are enlarged cross-sectional views partially broken
away of the cover positioned above the base and of the cover secured to the
base showing the enclosed development chamber, respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENT
 FIGS. 1-4b illustrate an apparatus 10 suitable for use in carrying
out the method of the present invention. The apparatus includes a
development compartment 12 formed between a central section of a base 14 and
cover 16 hinged to an upper portion 14a of the base. The bottom portion 12a
of the development compartment is provided with a heater in the form of
electrical elements 18 positioned above the base bottom wall 11 and within
an upwardly extending peripheral wall 12b terminating in a planar rim 14c
surrounding the lower portion of the development compartment. A porous pad
or sheet 20, such as blotter paper, containing the developer chemical
compound (to be described) is disposed over the heating element. A resilient
foam cushion 22 extends downwardly from the central portion of the cover and
seats within the wall 12b when the cover is closed to form the development
compartment within the peripheral wall and between the pad 18 and cushion
20. The development compartment may be of any convenient size. For example,
a compartment capable of accommodating an 81/2''.times.11'' sheet has been
found to be quite satisfactory.
 A power supply 24 is disposed within the upper section 14a of the
base and is arranged to supply ac current to the heating element 18 from a
standard ac outlet (not shown) at a selected temperature, via knob 24a, and
for a selected time via knob 24b, the implementation of which is within the
knowledge of those skilled in the art.
 A magnetic closure may be provided between the hinged cover and base,
e.g., by including a magnetic material along the border 16a and a ferrous
metal border 14b on the base (around the rim 14c), to provide a seal between
the cover and base to inhibit the egress of sublimated gases from the
chemical compound impregnated in the pad 20 to the atmosphere. See FIG. 4a.
 The following organic compounds have been found to be effective in
varying degrees in carrying out the method of the present invention:
 Nile Red (an oxazone dye),
7-(4-methoxybenzylamino)-4-nitrobenzozadiazole, carbazole, acridine and its
derivatives, rhodamine dyes, 2-(2-hydroxyphenyl)-benzoxazole,
2-(2-hydroxyphenyl)benzothiazole, coumarin compounds such as
4-hydroxycoumarin and coumarins 1, 2, 4, 6, 7, 30, 102, 120, 138, 151, 152,
153, 307, 314, 334, 337, 338, and 343, benzotriazole,
2-phenylbenzothiazole, 2-phenylbenzaxazole, 8-hydroxyquinoline,
8-hydroxyquinaldine, anthracene and its derivatives, naphthalene and its
derivatives, 4-(dimethylamino)cinnamaldehyde, fluorescamine, phthalic
dicarboxaldehyde, naphthoquinone-4-sulfonic acid, dansyl chloride and other
dansylated compounds, 4-chloro-7-nitrobenzofurazan,
5-chloro-2-methylbenzothiazole, chrysene, 4-hydroxybenzaldehyde,
nicotinamide, and camphor.
 There is some overlap between the above chemicals and those listed
under the Summary of the Invention. Such compounds are capable of
sublimating in sufficient quantities within a temperature range of about
100.degree. F. to 300.degree. F. over a short time interval, e.g., 30
seconds to several minutes, with the sublimated gaseous phase of the
compound capable of reacting with one or more of the constituents found in
the residues of latent fingerprints to form a discernable colorant or
fluorescent representation of the print. The term "short time" as used
herein is not to be considered limiting in the sense that an exposure time
of say one hour or possibly more would be beyond the scope of the invention.
Of the above, the preferred chemical compounds at the present time are Nile
Red and 4-(dimethylamino)cinnamaldehyde. However, additional investigation
will undoubtedly expand this list.
 In addition I believe that the following compounds would also
function as dry developer reagents to develop latent fingerprints in
accordance with this invention:
 Anthranilic acid, 1,4-naphthoquinone, benzanthrone, tetracene,
1,4-benzoquinone, and salicylic acid.
 The pad 20 is readily prepared by dissolving the chosen developer
compound, preferably substantially pure, in a volatile organic solvent such
as acetone or perhaps ethyl alcohol and simply soaking the pad 20 with the
solution and allowing the solvent to evaporate. The evaporated solvent
leaves behind finely dispersed crystals (or powder) within the fibrous
structure of the pad.
 In the alternative, the pad may be in the form of a pouch open at one
end with the chosen developer compound in crystalene or power form uniformly
dispersed within the pouch without the use of a solvent.
 To perform the method of my invention, the pad 20, so prepared, is
placed in the lower section of the development compartment 12, i.e., above
the heating element 18 of the above described (or equivalent) apparatus.
 A porous substrate, e.g., paper, in the form of a check or other
document, or a nonporous substrate, e.g., plastic disc or sheet bearing an
anticipated latent fingerprint is placed within the open development
compartment. The cover 16 is then closed, sandwiching the substrate
(preferably with the latent fingerprint specimen facing the developer pad)
between the foam cushion 22 and the pad 20. The temperature and exposure
time are then set (unless set at the factory) via the controls 24a and 24b
to allow the sublimated gas to develop the latent print. The temperature
setting will be dependent upon the developer compound used. For example, I
have found that a temperature of about 140.degree. F. is sufficient to
sublimate sufficient quantities of 4-(dimethylamino)cinnamaldehyde to react
with the amino acids inherent in latent print residues to provide a highly
fluorescent image of the latent print in about 30 seconds of exposure time.
This chemical reaction also suppresses interfering background fluorescence
common with some of the prior art latent print developing methods. Nile Red
requires a higher setting, e.g., about 220.degree. F. to selectively bind to
the oily components inherent in the sebaceous residues to provide a
fluorescent image. Fluorescent developer reagents generally provide higher
sensitivity than that of common, colorimetric reagents. The dry process in
general also has these advantages:
 1. The reagent is evenly distributed over the document
 2. There is no need for solvents, which may destroy the document or
the latent prints, produce a fire or an inhalation hazard, run inks, and
require time to dry
 3. In the vapor phase, the reactive "particles" are molecular in size
and therefore able to achieve much greater resolution
 4. The process is rapid (seconds compared to, in some cases, weeks)
 5. No mixing of chemicals
 6. No shelf-life limitations due to chemical instabilities
 7. Inexpensive in comparison chemical solutions
 8. No hazardous waste to dispose of and it can be used sequentially
with the traditional methods in widespread use today. It should be noted
that the developer reagent dispensing pad, properly prepared, will
accommodate the development of many latent prints, e.g., 50-100.
 There has been described a novel and highly useful method of
developing latent fingerprints. Various modifications are possible within
the generic principles disclosed by this invention.
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Have a GREAT week!