SMALL PARTICLE REAGENT - (S.P.R.)

Return to: Main Page   ||  Non-Porous Surfaces  ||  Sebaceous Techniques  ||  Metal Surfaces  ||  Glass Surfaces  ||  Plastic Surfaces  ||  Wet Surfaces  ]

Chemical Name:
SMALL PARTICLE REAGENT - (S.P.R.)
Surface Used On:
Non-Porous surfaces. Effective for use on wet items.
Sensitive To:
Sebaceous lipids & fatty components.
Development Color: Method to Record: Hazard: Protective Clothing: Fume Hood Use:

Dark Gray

Not.
Reagent Characteristics

Development Complete When:

Source of Error:

Incompatibilities:

Precautions:

Storage Container:

Safety:

Recommendations:


Similar Reagents



Sequential Reagents
(Not necessarily in this order.)



Abridged Reagent Sequence


Visual Examination
|
Forensic Light
|
Sudan black
|
*** S.P.R. ***
|
Forensic Light
|
Physical Developer

S.P.R. FORMULA:
SOLUTION #1:
4 g Choline chloride
8 ml Tergitol 7
500ml distilled water & Stir.

SOLUTION  #2:
10 g molybdenum disulfide
50 ml of solution #1 & Stir.

SOLUTION #3:
Add 900 ml distilled water
to solution #2 & Stir.

-- or --

(Combine the following
into a suspension:)

0.4 ml Tergitol (detergent)
  5  g Molybdenum disulfide
 50 ml distilled water

PROCEDURE OF APPLICATION
1.
a) Tray immersion - keep 
     stationary	for 1 minute.
	  -  or  -
b) Squeegee bottle application -
     Shake well and apply.
       Repeat for 1 minute.
2.
a) Tray rinse excess reagent in 
     tap water for 15 seconds.
          -  or  -
b) Tap water rinse under running 
     water for 15 seconds.
3.
   Allow the item to dry 
   at room temperature.
4.
   Photograph any developed 
   detail, then you may try
   lifting the dried print.	



Ridge Detail Visualized by:

Visible chemical/stain reaction.


Reagent Applicabilities:

Non-Porous surfaces
Post-Cyanoacrylate
Wet surfaces


Other Chemical Name(s):

S.P.R.
Molybdenum disulfide
Molybdenum disulphide


Working Solution Shelf-life:

Indefinite

Process Summary:

A reagent for latent print processing of items which are wet when recovered. Suggested for use on items where latent print powders are ineffective. This reagent can effectively work on items which have been soaked in liquid accelerants. The active ingredient (Molybdenum disulfide), which is applied either by spray or dipping. This technique requires a large work area that will be subject to messy conditions.

Accepted Deviations:

S.P.R. can be used as a post-cyanoacrylate process when dye stains are ineffective. Commercial kits are available, which can develop ridge detail in black, white or Ultra-violet. Application of the reagent may be repeated to enhance any faintly-developed ridge detail. The developed ridge detail may be lifted after being photographed.

Mechanically wiping the dried SPR residue off the treated surface with a paper towel may reveal latent prints not previously detected.

Supporting Reference Materials:

1. Minutiae Magazine, Summer Special 1994, Issue No. 24, pg.7.

2. Navarro, R.L., "Chemical Enhancement of Questioned Footwear Impressions", N.C. Bureau of Investigation, 1992, Page 53.

3. Advances in Fingeprint Technology 2nd. Ed., Lee, H.C. & Gaensslen, R.E., CRC Press, Boca Raton, FL., 2001.

4. Manual of Fingerprint Development Techniques 2nd. Ed., Home Office - Police Scientific Development Branch, White Crescent Press, Ltd., Luton, England, 2001.

5. Technical Notes, Lightning Powder Co. Inc., Salem, OR., 2001.

6. Almog, Frank A., "Modified SPR for Latent Fingerprint Development on Wet, Dark Objects", Jor. Forensic Ident., Vol. 43, No. 3, 1993.

7. Cohen, D. & Cohen, E.H., "A Significant Improvement to the SPR Process: More Latent Prints were Revealed after Thorough Wiping of Small Particle Reagent-Treated Surface", Jor. Forensic Ident., vol. 60, no. 2, Mar/Apl 2010, pp. 152-162.

Return to: Main Page   ||  Non-Porous Surfaces  ||  Sebaceous Techniques  ||  Metal Surfaces  ||  Glass Surfaces  ||  Plastic Surfaces  ||  Wet Surfaces  ]