Palm Prints and Print Processing Quiz 5 Flashcards
Palm Characteristics
3 Regions.
3 major creases (top, middle, left).
Left hand: Waterfall left.
Right hand: Waterfall right,
Palm Regions
Thenar (thumb).
Hypothenar (pinky).
Interdigital (fingers).
Interdigital Region
Wavy flow: ridges flow down, over, up, and out.
Tri-radii.
Tri-Radii
Convergence of ridges.
Ridges flow in, away, and up.
Looks like a delta.
Found primarily in the interdigital region, but also sometimes in the hypothanar region.
Hypothenar
“Writer’s palm”.
Down and out formations: ridges flow down and out from the interdigital to hypothenar.
Edge creases: more defined and different directionality than thenar edge creases.
Fingers: General
Ridge flow of fingers is inner to outer.
1 crease between 1st and 2nd joint.
2 creases everywhere else.
Fingers: First Joint
First joint always has a pattern.
If no observed pattern, it is not the first joint.
Fingers: Third Joint
Down and out ridge flow on index and pinky.
Wavy ridge flow middle and ring.
Has hash marks and flexion creases.
Fingers: Second Joint
Second joint ridges in a linear fashion.
Follow flow of arrows.
Skin Conditions
Displasya.
Psoriasis.
No ridges.
Displasya
Refers to an abnormality in the mutation of cells within a tissue.
Latent
Hidden. Refers to any print that must be enhanced chemically or physically to be made visible.
Leaving a Latent Print
Simply sweat exuded from the body.
Friction ridge skin does not exude oil. If present, it is picked up from another area of the body.
Basic Types of Print Processing.
Physical.
Chemical.
Types of Physical Processing
Powdering.
Mikrosil/Accutrans/Forensic Sil.
Types of Chemical Processing
Cyanoacrylate Fuming (Super-glue). Ninhydrin. RAM. Rhodamine. Ardrox.
Powdering
Application of finely ground colored powder.
Always on a non-porous surface.
Makes latent prints visible.
Powdering: How it Works
Powder clings to moisture, oil, or other residues left behind when friction ridges touch an object.
Characteristics of Powder
Passable through 200-mesh screen.
Possesses adhesive qualities.
Free-flowing and non-clumping.
Not caustic, toxic, or carcinogenic.
Powdering: Surfaces
Best used on smooth, non-porous surfaces.
Glass.
Metal.
Finished Wood.
Plastics.
Not suitable on wet, rough, or tacky surfaces.
Powdering: Considerations
Always consider effects of powdering on forensic exams.
Before using powder, conduct careful visual examination of each item.
Powdering: Order
Powder applied after super-glue process.
Once an item has been powdered, no further latent print examinations can be performed.
Powdering: Colors
White.
Gray/Silver.
Black.
Magnetic.
Other Powders
Different types of toner (Xerox). Granular powders in red, bronze, gold, etc. Fluorescent powders (not recommended for use by FBI ERT for field processing.
Fluorescent Powders: Properties
Redwop, Greenwop, etc.
Granular in flake and shape.
Excited by ALS.
Not as sensitive as other powders.
Fluorescent Powders: Cautions
Can over develop and ruin latent prints.
Do not lift well and difficult to photograph.
Must use a feather duster and light source.
Zephyr Fiberglass Brush
Picks up and retains supply of powder.
Filament ends become softer with use.
Over 1,000 fiber bundles.
Over 100 individually treated fiberglass filaments.
Other Brush Types
Camel or Squirrel hair brushes.
Much more abrasive than glass fiber and not recommended for application of powders.
Only use if no other brushes are available and on prints that have been super-glued.
Other Powder Application Methods
Cotton (effective on large surfaces).
Feather duster.
Magnetic wand.
Choosing a Powder Color
Choose a color that will contrast with he surface being powdered.
Black on light.
Gray/White on dark or reflective surfaces (for photographic surfaces.
Lift
Usually tape or similar type of substance which contains the correct amount of adhesiveness to remove enough of the powder without destroying the original print impression.
Function of Lifts
To preserve crime scene prints.
Act as a negative from which photographic copies can be made.
Use as an exhibit in court proceedings.
Can be directly scanned into AFIS systems.
Mikrosil Composition
Consists of filler substance (usually white or brown) and a hardening substance.
These must be mixed together and applied with tongue depressor.
Sets in only a few minutes then peels off surface.
AccuTrans
Used by FBI Laboratory. Clear, white, or brown. Polyvinylsiloxane casting material. Does not require mixing. Sets in 4-8 minutes (50-68 degrees).
Cyanoacrylate Fuming
Super-glue. Used for latent print enhancement. Accidentally discovered in 1979. FBI began using it early 1980's. Fuming works through volatilization and polymerization reactions.
Cyanoacrylate Substrate Types
Works especially well on non-porous items (plastic, garbage bags, aluminum, glass, etc.)
Also works on semi-porous items (glossy paper, rubber gloves, styrofoam, etc.)
Volatilization
Occurs when liquid super glue vaporizes.
Reaction can occur at room temp, but takes a long time.
Increased temperatures decreases time needed.
Polymerization
Super glue vapors bind to moisture in latent prints and form plasticized impressions.
Overexposure of items cause vapors to attach to entire surface and obscure print impressions.
Microburst Fuming Method
High heat.
Lots of cyanoacrylate.
Short period of time.
Fuming Instrumentation
Misonix fuming chambers.
CBC (cyanoacrylate blowing chamber).
Hand held fuming wand.
Microburst Processing Procedure: Equipment
Cyanoacrylate ester.
Aluminum dish.
Fuming chamber.
Microburst Processing Procedure: Steps
Set fuming chamber at 400 degrees Celsius.
Amount of cyanoacrylate depends on size of chamber and amount of time items will be in chamber.
Our Misonix chamber uses a quarter-sized amount.
Line of Sight Process
Superglue vapor will only react to exposed surfaces.
Set or hang evidence to minimize surface area being blocked.
Microburst Processing Procedure: Advantages
Excellent preservation method.
Acceptable to underfume an item - the superglue process can be repeated.
Microburst Processing Procedure: Disadvantages
Do not overfume items: ridges and furrows will become filled in with super glue and the print will (most likely) be destroyed.
Ninhydrin
Triketohydrindene hydrate.
A powder that is mixed with ethyl alcohol, methyl alcohol, acetone, or petroleum ether before applying to items of evidence.
Dyes amino acids in the perspiration left by friction ridge skin a light purple.
Ninhydrin: Application
Solution is applied to the paper either by dipping the paper into the solution or spraying the solution directly on the paper.
ALWAYS wear gloves!
Ninhydrin: Print Development
Prints will spontaneously develop over time (12-24 hours).
Faster development can occur with the application of heat and humidity (steam iron).
The latent print developed color is called Rheuman’s Purple.
Requires only small amount to amino acids to react.
Ninhydrin: Uses
Used on paper and other porous items.
Can also e used as a blood reagent.
Prints on Paper
Paper is one of the best surfaces for chemical development of latent prints.
Almost any type of paper can produce latent prints with ninhydrin (except paper towels).
RAM
A fluorescent dye used to stain cyanoacrylate developed latent prints.
Composed of Rhodamine 6G, Ardrox, and MBD.
Developed in 1990 by Fingerprint Specialists in the FBI Latent Print Unit.
RAM: Processing Procedure
Can be applied by spraying, squirting, or dipping.
Can only be used on surfaces that have been superglue fumed.
Most effective of non-porous/semi-porous surfaces.
RAM: Light Sources
RAM used in conjunction with LASER and alternative light sources.
Optimum spectrum range for viewing RAM developed latent prints is 365 nm to 535 nm.
RAM: Observing Under Light Sources
Suggested filter for initial examination is 550 nm (orange).
Use all appropriate/available filters (530 nm, 540 nm, 550 nm, and 570 nm).
RAM: Benefits
Additional processing step before powder.
Excellent visualization of latent prints on light/white/multi-colored items.
Covers multiple wavelengths of fluorescence.
RAM: Fading
Prints can fade over time, so they must be photographed in a timely manner.
Rejuvenation of a latent print is possible by reapplication of RAM, but does not always take place.
RAM: Shelf Life and Storage
RAM working solution is stable for approximately 6 months.
All of the solutions should be stored in dark bottles.
WetWop
Develops latent prints on the adhesive side of tape.
Small Particle Reagent
Develops latent prints on objects that have been immersed in water.