Aqueous Leucocrystal Violet
Introduction
Aqueous Leucocrystal Violet
(ALCV) can be used to enhance and develop latent prints stained
with blood on porous and nonporous surfaces. It can also be
used to stain blood marks of shoeprints, swipes and other contact
to track where a suspect or victim walked, was dragged, or somehow
came in contact with the surface. It will not stain the normal
constituents found in latent print residue so it should only
be used in the case of blood-contaminated latent prints to be
successful. This solution is an indicator for blood, however,
it may react with other substances not specific to blood.
Safety
As with all chemicals,
always read the MSDS (material safety data sheet) to learn about
the safe handling and health hazards of each chemical. Nitrile
or chemical gloves and protective clothing, such as disposable,
Tyvek® lab coats or coveralls, should be worn when using
Aqueous Leucocrystal Violet at the crime scene. It should be
used with a mist respirator if the product is being sprayed
at the scene. In the laboratory, this solution should be used
in a fume hood. Some of the solvents used to mix it are hazardous
and/or corrosive. Use the proper safety precautions in handling
and disposal. Because this solution is used on surfaces contaminated
with blood, the proper safety precautions for disposal of biohazards
must be considered.
Mixing Instructions
There are three bottles
in the kit containing pre-measured chemicals. The large bottle,
A, contains the Fix Reagent, a liquid. Bottle B contains the
dry Leucocrystal Violet and Bottle C contains the dry Sodium
Acetate. Start by adding about 30 ml (1 ounce) of the liquid
Fix Reagent (Bottle A) to the bottle of Leucocrystal Violet
(Bottle B). Put the cap on the bottle and shake vigorously for
about 2 to 3 minutes. Pour the contents of this bottle (Bottle
B) into the large bottle (Bottle A) and shake it.
Now, pour about 30 ml (1
ounce) of the liquid in the large bottle (Bottle A) into Bottle
C containing the dry Sodium Acetate. Put the cap on Bottle C
and shake vigorously for about 2 to 3 minutes. Pour the contents
back into the large bottle (Bottle A). Put the cap back on Bottle
A and shake thoroughly.
Processing Instructions
Prior to applying Aqueous
Leucocrystal Violet, it is recommended to do a presumptive test
for blood and to collect a sample of the suspected blood, if
visible, for DNA or other blood-type testing. However, the general
rule is to take the fingerprint evidence over the blood evidence.
Aqueous Leucocrystal Violet
can be applied to porous or nonporous surfaces, such as paper,
metal, plastics or glass. Aqueous Leucocrystal Violet is best
applied by either submersion or by washing the solution over
the surface in question. It is NOT recommended to spray Aqueous
Leucocrystal Violet except in the case of carpeting to observe
shoeprints or other marks in blood. The development will begin
to occur within 30 seconds. Then, blot with paper towels, tissues
or even toilet paper if that is all that is available, to remove
the excess reagent. Begin by spraying lightly with a fine mist
to avoid overdevelopment.
Processing Instructions
- Vertical Surfaces
Tape or affix a length
of non-textured paper towel material over the wall or other
vertical surface. (A textured paper towel may leave its pattern
in the latent print.) Wash the Aqueous Leucocrystal Violet solution
over the paper towel, allowing it to make total contact (no
air bubbles) with the vertical surface. After about 30 seconds,
remove the paper towel and observe the surface. Use caution
with some plaster and stucco walls, as the solution may stain
the entire surface. Also, direct sunlight can cause unwanted
background development, so photograph any developed prints or
stains as quickly as possible.
Processing Instructions
- Horizontal Surfaces
Aqueous Leucocrystal Violet
solution can be washed directly on the floor or other horizontal
surface. After about 30 to 60 seconds, blot with tissues or
paper towel material.
Sequential Processing
The first process suggested
is to use fluorescent powders (choose the color most appropriate
for the background fluorescence). Then use Aqueous Leucocrystal
Violet and then, Physical Developer. It is suggested to photograph
any latent prints developed with each process before treating
the evidence with a new process. The Physical Developer may
or may not enhance the bloody latent prints, but it may develop
other latent prints. Each chemical reacts with different components
of the blood residue.
Photography
Photography of latent prints
developed with Aqueous Leucocrystal Violet should not pose any
problems if the surface background is a light color. If the
surface is a dark color but will fluoresce, it may be beneficial
to use fluorescence examination to enhance the photographic
contrast. One recommended method is to use a Forensic Light
Source set between 550 and 600 nm, view with red goggles and
photograph with a dark red filter, such as a Tiffin or Wratten
25 or 29.
Storage and Shelf-life
The unmixed Aqueous Leucocrystal
Violet Kit of three bottles has a shelf-life of at least one
year. Once it is mixed, the shelf-life is approximately 3 months
if stored within an office environment. If the mixed solution
is stored in a vehicle in hot temperatures, the shelf-life will
be considerably less.
Disposal and Cleanup
Since any crime scene or
piece of evidence is suspected to have blood on it when used
with this solution, the greater hazard of the blood dictates
its disposal and cleanup. Clean any surfaces and blotting tissues
in accordance with the regulations for cleaning the biohazard
of blood. Bleach may clean some of the staining from Aqueous
Leucocrystal Violet. If repainting walls, use an epoxy-type
paint to seal it.
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