Download SIRCHIE® TECHNICAL INFORMATION

TI02-46ENG-REV4
SIRCHIE
®
100 HUNTER PLACE
YOUNGSVILLE, NC 27596 USA
Phone: (919) 554-2244, (800) 356-7311
Fax: (919) 554-2266, (800) 899-8181
Finger Print Laboratories
Website: www.sirchie.com
E-mail: [email protected]
TECHNICAL INFORMATION
Physical Developer
Catalog Nos. LPD100, LPD101
INTRODUCTION
Physical Developer is a silver-based aqueous reagent that
reacts with components of sebaceous sweat to form a silver/gray
deposit. The process is effective on porous surfaces such as
paper, cardboard, raw wood, tissue paper, paper-based adhesive
tapes, and some man-made fibers. It is seldom used as the
primary method of latent print development; rather, it is used
as a follow up to processing with DFO and/or Ninhydrin. Since
it reacts with sebaceous compounds, it is often likely that additional prints or detail will develop that were not discovered
when using other processes that react with amino acids. Physical
developer is not suitable for use on non-porous surfaces.
Physical developer may interfere with forensic examinations
of handwriting, inks, indented impressions, body fluids including DNA profiling, fibers, hairs, paint and other examinations.
Physical Developer is a sensitive, complex formula requiring
special handling. Use of this product should be limited to experienced personnel only.
BACKGROUND
Physical Developer contains chemicals that can be harmful
and fatal if taken internally. The material can be used safely
if all precautions listed herein and in the Material Safety Data
Sheets (MSDSs) are followed completely. Sirchie supplies Physical Developer in two-part, pre-mixed containers. Solution “A” and Solution “B” should not be combined until just prior to use.
Some forensic laboratories have recommended an acid pre-treatment prior to using Physical Developer. We
have pre-treatment formulas for those wishing to use them. Physical Developer will develop latent prints known or
suspected to be several years old.
PRECAUTIONS
Before using this kit, consult the appropriate Material Safety Data Sheets (MSDS) found on our website at
www.sirchie.com and click on MSDS.
Wear protective clothing (lab coat or apron), non-porous gloves and safety glasses when preparing or using this
reagent.
Avoid exposure to the skin. Oral ingestion of silver nitrate can be fatal.
Collect used Physical Developer solutions in an appropriate container for disposal by the proper authority. If
the item(s) is of no further forensic or evidential value, articles treated with Physical Developer may be returned to the owner or discarded as ordinary waste.
Physical Developer is especially sensitive to any contamination present. Be certain to wash all containers to
be used in warm, soapy water. Rinse thoroughly with tap water then rinse three times with distilled water. Any
residual chlorine from tap water may cause adverse reactions with the silver compound in Physical Developer.
Wet documents that have soaked in the following solution(s) can be very fragile. Use extreme care when
handling these specimens. If possible, use tweezers or tongs that do not have serrated tips to prevent leaving
indentations in the paper that may cause it to tear.
If you are performing a sequence of examinations, begin with DFO, and then examine with UV light.
Ninhydrin treatment should follow. Physical Developer should be the last step, and no further treatment with
other chemicals should be attempted.
Copyright© 2008 by SIRCHIE® Finger Print Laboratories, Youngsville, N.C.
All Rights Reserved.
TI02-46ENG-REV4
PROCEDURE
CAUTION: Solutions “A” and “B” should not be mixed together until you are prepared to process evidence
for latent fingerprints. If stored in a darkened cabinet, the shelf life of the combined solutions is several days,
depending on the depletion of the silver nitrate component. Depletion of the silver content can be anticipated if
a large number of items are processed, and this, of course, will shorten shelf life and usefulness of the solution.
Uncombined solutions can be stored at room temperature (or cooler) until the date stamped on Solution “B” has
passed (approximately six months). Do not use Solution “B” after the expiration date. Do not transfer either Solution “A” or “B” to other containers of clear glass or plastic as these reagents are light sensitive and will degrade
and will lose their effectiveness.
Preparation of Physical Developer Working Solution
1. Physical Developer (PD) working solution is made by combining one (1) part Solution “A” with eighteen (18)
parts of solution “B” in a clean glass or plastic tray (do not use metal trays) and stirring with a glass or plastic
rod, or agitating for approximately one (1) minute.
2. The following are examples of measured quantities of working solutions:
Solution “A” 5 ml
20 ml
50 ml
Solution “B”
90 ml
360 ml
900 ml
3.Prepare only as much working solution as is necessary to cover the item being processed with a depth of about
5 mm of solution.
Formula for Preparing A Pre-Treatment Stock Solution
Caution: Be certain to consult the MSDS for the following chemical prior to mixing and use. Some laboratories recommend and use a pre-treatment solution.
1. Using a clean, 2 liter glass beaker, add 1 liter of distilled water.
2. Add 25 grams of MALEIC ACID and stir with a magnetic stirrer until all of the solid material is dissolved.
3. Transfer the MALEIC ACID solution to a clean container. Unused MALEIC ACID solution will keep indefinitely. Place an appropriate label on the container.
4.Recommended pre-treatment involves allowing the document to soak in the MALEIC ACID solution for up to
10 minutes or until all bubbling action stops.
5. Follow instructions for processing with Physical Developer.
Processing Evidence With Physical Developer
Use a clean glass or plastic tray. The kinds of trays used in darkroom processing are ideal.
1. Place the specimen (document, envelope, etc.) into the working solution prepared above.
2. If latent fingerprints are present, they will begin to develop in about 5 minutes. Remove the specimen from the
solution when the background begins to develop to a significantly dark color—usually about 15 minutes. Overdevelopment will cause the latent prints to lose contrast with the background color.
3. After removing the specimen from the developing tray, carefully place it in a second glass or plastic tray, and
then rinse with running water for about 5 minutes to prevent excess staining.
4.Remove the item from the rinse tray, and allow it to air dry at room temperature.
5. Photograph any useful prints after the specimen is completely dry.
6. Low contrast prints may be improved by reprocessing, but only after photography is complete.
7. To reprocess specimens, remove any residual chlorine (from tap water) by immersing the specimen in distilled
water. (Reprocessing should take place within a few hours after the original developing procedure.) If reprocessing is to be attempted, do not use any pre-treatment. Repeat steps 2
to 5 above.
8. When processing is complete, to prevent staining, wash and rinse all
trays and utensils used in the process.
Photography
Latent fingerprints developed with the Physical Developer process
are gray in color and do not usually present any particular photographic
problems. Diffused illumination is usually satisfactory, but in some cases
oblique lighting may be useful. The use of high contrast lithographic films
may be useful if the latent prints are very faint.
Fluorescent examination may also prove useful, particularly if a confused background is present. On some materials, the background may also
fluoresce and the developed prints will absorb the illuminating light. Use
of an alternative light source is recommended, due to its wide spectrum of
UV light.