1. Print Development Methods
Fingerprints Part IV
Print Development Methods

2. Fingerprints and DNA DNA from fingerprints.
For DNA analysis to be successful, try to collect at least 100pg of DNA
Each cell has about 6pg
Need about 100/6 = 16 cells
Most fingerprints have < 100pg
Only about 20% of fingerprints have sufficient amounts of DNA

3. Fingerprints and DNA Take Powder from Secondary Source
Create Secondary Powder Source by removing
Powder from original container to secondary container
British studied powder dusting on ability to obtain usable DNA profiles.
Lifting using traditional lifting methods – tape and gels - does not quantitatively capture the DNA.
After lifting, swab lifted area
to collect remaining cellular material.
Can still get DNA profiles using sensitive DNA analysis techniques from lift and swabs taken from the lifted area.
Probably no relationship between amount of fingerprint residue present and amount of DNA present.
Related to a person’s ability to shed cellular material.
Referred to as shedders
Take Powder from
Secondary Source
Original Powder Source
Secondary Powder Source
Slim possibility of contaminating a fingerprint’s DNA with another after using the same brush and powder …
Use clean brushes and fresh powder between dusting.
Do not mix used and fresh dusting powder by releasing the used powder into the original reservoir.

4. Specialized Physical Methods

5. Wet/dry Surfaces Small Particle Reagent (SPR)
Suspension of molybdenum sulfide grains
Size of crystalline particles is critical
In mild detergent solution (Kodak Photoflo or 1 drop of Dawn in Quart)
Alternatives to molybdenum
Iron oxide
employed with varying success
Zinc carbonate
tried on dark surfaces (particle size important)
Some fluorescent compounds, too
Two fingerprints on a car, developed with SPR.
Works well on non-porous dry surfaces
Plastic bags/wax paper/glass/painted surfaces/water-soaked firearms
Adheres to fatty components of latent
Used in a sequence approach
Used for items cannot be dried prior to processing
Useful for sticky-side development

6. Vacuum Methods

7. Vacuum Methods Vacuum metal deposition (VMD) – Columnar Thin Films (CTF)
Smooth nonporous surfaces
Plastic bags/plastic packaging material/smooth surfaces
Drawbacks
Equipment is expensive
Sample chamber is small
Procedure
VMD - Evaporates Gold and then Cd or Zn in vacuum chamber
Thin metal film deposited onto print
CTF – Can work with other methods – Superglue fuming
How VMD Works
Fingerprint ridge
Vacuum Deposited Gold
Vacuum Deposited Zinc or Cadmium

8. Columnar Thin Film (CTF) Development A Measure of Topology
Developed in 2009
Lahktakia & Shaler
Columnar Thin Films of Deposition Material onto Fingerprint residue
Thermal Evaporation of Deposition Material
Chalcogenide glass
MgF2
Gold/Silver
AlQ3 – fluorescent
Tops of Columnar Columns
Looking Down on CTF Ridge
Columns
Fingerprint Ridge

9. Requires Active Chemical Molecules in Print Residue
Superglue Fuming
Requires Active Chemical Molecules in Print Residue
Water
Amino Acids
Lactate

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Superglue Fuming
Two methods
Heat & Humidity vaporization of superglue
Vacuum vaporization of superglue
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11. Heat & Humidity Super Glue Fuming
Microburst Method of FBI

12. A: Fresh Clean Print B: 2- Day Oily Print
FIG. 2—(A) SEM image of a fresh, cyanoacrylate fumed clean print at a 5000~ magnification; (B) SEM image of a cyanoacrylate fumed two-day-old clean print at a 5000~ magnification. The print was aged prior to fuming.
Clean prints were prepared by thoroughly washing, rinsing, and drying hands, and swiping thumbs with ethyl alcohol. Oily prints were prepared by swiping a cleaned thumb across oily regions (forehead, nose, neck, or hair) prior to placing the print on the development medium.
REFERENCE: Lewis LA, Smithwick RW III, Devault GL, Bolinger B, Lewis SA Sr. Processes involved in the development of latent fingerprints using the cyanoacrylate fuming method. J Foren­sic Sci 2001;46(2):241–246.

13. Images of the polymer formations developed
30 sec
20 sec
45 sec
120 sec
Images of the polymer formations developed
during the cyanoacrylate fuming of a clean print.

14. Fresh Oily Print 2-Day Oily Print
A: Image of a fresh, cyanoacrylate fumed oily print at a 5000~ magnification;
B: SEM image of a cyanoacrylate fumed two-day-old oily print at a 5000~ magnification.

15. Vacuum Superglue Fuming
Developed Watkin & Misner 1990
Nat’l Res. Council of Canada
Technique
Large metal chamber with object to be printed
With small quantity of superglue
Pressure reduced to 200 mtorr (0.2 torr)
Std atmospheric pressure 760 torr (760,000mtorr)
Accelerates vaporization of superglue
Reduces time to deposit reduced about 20 min.
Characteristics
Prints translucent – weakly
Sharper ridge detail & more pore detail
More uniform prints
Less risk of overdevelopment
Vaporization can be used to develop prints not directly exposed
Inside of plastic bags
Not applicable to:
Cans/bottles because they may explode
Nothing wet

16. Visualizing Superglue Prints
Super Glue Polymer has no significant absorption band
Visualizing Superglue Prints
Depends on color of object
Choose opposite to color of exhibit’s surface
Using Light
ALS
White light or 450nm for initial examination
May need oblique lighting
Reflective UV light
RUVIS
Light ridges against dark background
Staining – fluorescent dyes
Dusting – various powders
Instrumentation
SceneScope - imager uses intensified UV reflectance instead of fluorescence
Not an ALS (Alternate light Source)
Detects fingerprints (and footwear impressions) on most non-porous surfaces prior to any treatment or after cyanoacrylate fuming.

17. Visualizing Superglue Fumed Prints Enhancement with Fluorescent Stains
Solvent for fluorescent stain is important
Must soften the polymer
Allows penetration of stain without damaging the print image
Water rinse after staining
Preferred for
Non-luminescent surfaces
Dark and/or multicolored
Most popular Dyes
Rhodamine 6G
Ardrox 970-P10
Basic yellow 40
Mixtures of Dyes for colored surfaces
StarDrox
RAM
Not suitable for:
Porous surfaces
Semi-porous surfaces

18. Adhesive Tapes

19. Always Assume Prints present on smooth AND the sticky-sides.
Tapes are important because routinely used to seal boxes, letters and packaging.
Also used to restrain people.
Two distinct surfaces, each with unique development issues.
Easy for fingers to stick to sticky side of tape - print impression transferred to tape.
Latent print can be on smooth side of the tape.
Developing fingerprints on the sticky-side of tapes has presented developmental problems. Traditional dusting powder does not work because it sticks to the adhesive and masks prints that might be present.
Scientists and investigators developed variety of methods for developing adhesive-side prints.
Must determine chemistry of sticky-side of tapes
Affects subsequent print development.
Rule of thumb
Tapes should be collected … preserved … taken to laboratory for print development … especially if tape stuck to itself.
Rare instances when this is impossible
Un-sticking tape and developing the prints on-scene is necessary.

20. Adhesive Side Print Development
Several techniques available or sticky-side of tapes:
Small Particle Reagent (SPR),
Black and white WetWop,
Sticky-side powder,
TapeGloTM ,
TapeGlo is a fluorescent dye
Gentian violet,
Gentian violet (Basic Yellow 3): stains fats.
Iron oxide powder-based suspension and others
Powder-based suspensions in a dilute detergent solution.
No Technique develops prints on all adhesives all of the time
Tape adhesives categorized: Rubber or acrylic-based
Chemically, adhesives differ … why powder suspensions and chemical formulation development techniques work with one type of tape and not another.
Masking tape represents a third category … Porosity creates problems for print development.

21. Spot Testing Adhesives
Apply a toothpick-sized but clear spot of black or white powder suspension to a section of the tape that is less likely to have been handled.
Wash the spot and only that area of the tape with tap water until the excess powder is gone.
If powder remains on the spot, the adhesive is PROBABLY acrylic-based and should be developed using an aqueous version of Basic Violet 3 (Gentian Violet).
If the tape is visible through after washing the test spot, it is probably a rubber-based adhesive and should be developed using powder

22. Tapes – Sticky Side Rubber-based adhesives – Use powder suspensions
SPR
WetWop
Iron Oxide suspension
Acrylic-based adhesives –
Basic Violet 3
WetWop
SPR

23. TapeGlo™ TapeGlo™ : A fluorescent dye.
Contains no hazardous or flammable liquids
No fume hood is required
Shelf life is approximately six months
Pour TapeGlo™ into a dipping tray or spray on the adhesive surface.
Fluoresces best when viewed between 488nm and 540nm.

24. Removing Tape from its Substrate
Physical processes.
Pulling apart:
Fastest method … causes least damage to the underlying prints. Tedious and there is always the possibility of distorting the tape … alter underlying prints if surfaces – tape and surface – are tightly bound.
Not recommended without a good reason.
Cooling (Freezer)
Many recommend cooling to un-stick from surfaces OR to un-stick them from themselves. … Freezing using liquid nitrogen or a microcircuit freezing spray. … Cool below the adhesive’s critical ‘glass transition temperature.’ … liquid nitrogen … dry ice. Adhesive solidifies … gently and slowly pulled from the surface or from the sticky-side of an adhering adhesive. Essentially the frozen adhesive ‘fractures’ from the surface to which it is bound.
Freezer Spray
Tantamount to freezing. Electronics industry use these sprays … replace liquid nitrogen for separating adhesives from various surfaces … except from other adhesives. Temperature in the -65oF range, so precautions are necessary: wearing appropriate PPE: gloves, face mask, protective clothing.
Solvents.
Hydrocarbon-based solvents recommended for adhesives stuck to other adhesives: UnDoTM. Slow and tedious … use tiny amounts of solvent because too much will dissolve the adhesive and ruin prints.

25. Freezer Spray For localized, small areas of tape.
Method of choice for removing adhesive tapes from plastic bags and other plastic material.
Will freeze skin – use thermal gloves.
Not for removing adhesive from paper, cardboard or from adhesives adhering to adhesives.
Solvents:
Removing adhesives from adhesives using solvents should be done carefully.
Alternative method for disengaging adhesives from paper and cardboard and for separating adhesives from adhesives.

26. Super Glue for Adhesive Surfaces
Low-level fuming (vacuum)
Fluorescent staining
Basic Yellow 40 staining
RAM
An alternate for gentian violet
SPR after SG fuming
Powder dusting
Sticky-side Development
Variable success
Type of tape
Thickness
Consistency of the adhesive
Easily overdeveloped
Loss of print detail & poor contrast
Super glue fume prints on the smooth side of tape before working on the adhesive side.
Fingerprints on smooth side destroyed during cooling with Freezer Spray by condensation
Super glue fuming can develop prints on both the smooth and adhesive side of tapes.
After developing smooth-side with superglue, photograph then lift
Then use freezer spray.

27. Enhancing Bloody Fingerprints

28. Special Situations Bloody Fingerprints
Considerations
DNA
How fingerprint made:
Contaminated with blood or already on surface developed by the blood
Positive or negative print?
Pre-existing sebaceous prints repel blood
Sebaceous (greasy) print
Blood repelled by ridges & accumulates in furrows
Ridge detail may not be sufficiently defined for comparison
Use protein stain reagent
Most do not interfere with DNA

29. Bloody Fingerprints Chemical Enhancement – Protein Staining Reagents
Procedure
Sprayed or squirted from wash bottle or immersion
May require de-staining using organic solvents
Protein staining reagents
Amido Black 10B (Naphthol blue black B)
Organic formulation
Immersion 30 seconds
Washing in organic solvents (methanol)
Ethanol/water wash solution is field useable
Blue/black stains
Aqueous formulation
Coomassie Blue R250
Less hazardous
Can be used with gel lifters after impregnating with dye
Possible alternatives
Acid Violet 17 (coomassie brilliant violet)
Benzoxanthene yellow (luminescence in weak blood)
Bloody fingerprint photographed on human
skin with the aid of an alternate light source.

30. Sequence Detection Prints in Blood
Dark or Shiny
Background
Light
Background
Observe via
Diffused reflection
mode
Observe via
Absorption (415nm)
mode
Visible as light ridges
Against dk. bkgrnd
Visible as dark ridges
Against light Bkgrnd
DFO
Examine in
Luminescence Mode OR
Protein Stain
Acid Violet 17 or Amido Black
Photography

31. Partial Bloody Print Developed with Crystal Violet (left) & CTF ®
with Coomassie Blue