1. Take out your notes (HW) and keep it at your desk.
Monday, 12/16
Homework Quiz
Take out your notes (HW) and keep it at your desk.
Take a quarter sheet of scratch paper and put your name and class period on the top.
You do not need to copy the questions, your responses do not have to be in complete sentences.

2. List the three types of fingerprints that are found at crime scenes.
What does RUVIS stand for and what is it used for?
What are three types of powders used to develop prints?
Which type of chemical treatment was developed first?
What is the first thing that a criminalist must do after visualizing a print but before any attempts are made to preserve it?
When you are done:
Put your quiz in the HW folder
Keep your notes at your desk

3. Methods Of Detecting Fingerprints
Objectives:
Distinguish visible, plastic, and latent fingerprints.
List the techniques for developing latent fingerprints on porous and nonporous objects.
Describe the proper procedures for preserving a developed latent fingerprint.

4. Distinguish visible, plastic, and latent fingerprints.
Visible prints: Made when the finger deposits a visible material such as ink, dirt, or blood onto a surface
Plastic prints: Fingerprints impressed into a soft surface
Latent (invisible) prints: Caused by the transfer of body perspiration or oils present on finger ridges to the surface of an object

5. Locating Fingerprints
The method of visualization is determined by the type of surface being examined:
Hard/nonporous surfaces: Powders and Super Glue fuming
Soft/porous surfaces: Chemical treatment
RUVIS (Reflected Ultraviolet Imaging System)
Aims UV light onto a non-absorbent surface to help locate fingerprints
Prints are then developed in the appropriate manner

6. List the techniques for developing latent fingerprints on porous and non-porous surfaces.
Powders (grey/black, metallic, fluorescent)
Chemical methods:
Iodine fuming
Ninhydrin
Physical developer
Super Glue fuming
DFO
Fluorescence

7. Powders Used mostly on dry, nonporous surfaces
Applied with camel’s hair or fiberglass brush
Powders adhere to the perspiration and oil residues left by the ridges
Grey/black:
Most common
Used on lighter surfaces
Magnetic:
Less damaging to print
Good for leather and rough plastics
Fluorescent:
Used in conjunction with UV light
Prevents prints from being obscured by color of the surface

8. Iodine Fuming Oldest of the chemical methods Process:
Iodine crystals and suspect material placed in a cabinet and heated
Iodine goes directly from solid crystals to a gas (sublimation) when heated
Vapors combine w/ the print to make it visible
It is thought that the iodine combines with fatty oils or residual water in the fingerprint, but not known for sure
Prints that are developed using iodine fuming are not permanent
Can be extended by a month to a year with the application of a 1% solution of starch in water

9. Ninhydrin Process: Sprayed onto porous surfaces
Frequently used on paper documents
Purple/blue prints will appear w/in 1 to 2 hours after application
Chemical reaction occurs with amino acids in the deposited perspiration

10. Physical Developer Silver nitrate-based liquid
Used for visualizing latent prints undetected by previous methods
Good for porous materials that may have been wet at one time
Should be the LAST method used
Washes away traces of proteins from an object’s surface
Order of application:
Iodine Ninhydrin  Physical developer

11. Super Glue Fuming
Most useful for nonporous surfaces such as metals and plastics
Process:
Super Glue (cyanoacrylate) heated in enclosed chamber with suspect material
Expose for about 6 hours
Is developed when the glue adheres to the print and gives it a white appearance
Fuming wands are available for more convenient development on larger surfaces
Has been used to develop prints in small, enclosed areas such as the inside of a car

12. Super Glue Fuming

13. Fluorescence
1st – Discovered that fingerprints could be visualized by exposure to laser light
2nd – Fingerprints could be treated with chemicals that would induce fluorescence when exposed to laser light
Chemicals that could be applied after development (zinc chloride after ninhydrin, rhodamine G6 after Super Glue fuming)
3rd – Lasers were no longer needed to induce fluorescence as it was now chemically induced, and high-intensity or alternate light sources could be used to visualize prints

14. Alternative light sources
High-intensity
Alternative light sources
Quartz halogen
Xenon-arc
Focused using fiber-optic cables
Can utilize several filters giving the flexibility to select different wavelengths of light
Light-emitting diodes (LEDs)
More portable

15. Additional Processing Information
Chemical agents do not interfere with DNA tests
Ideally, all processing and development of prints should be done in the laboratory and NOT at the crime scene

16. Preservation of Developed Prints
Once developed, fingerprints must be preserved
Before preservation  fingerprints must be photographed FIRST!
Close-up of fingerprint
Expanded shot for overall location of the fingerprint
2 possible procedures:
Small objects:
Preserve object w/ print in its entirety
Cover print w/ cellophane
Large objects:
If developed w/ powder, lift print w/ adhesive

17. Digital Imagining For Enhancement
Photographs are turned into digital files
The larger the # of pixels, the more closely the file will resemble the real-world image
Allows for the removal of background color interference
More reliable hits in AFIS
Easy creation of fingerprint comparison charts

18. Digital Imagining For Enhancement