Transcript DEVELOPMENT REVIEW

DEVELOPMENT REVIEW
• The type of surface on
which a fingerprint is
deposited has a lot to
do with the type of
print that will be
deposited on the
physical evidence
• The use of sequential
processing techniques
can increase the
number of prints
found and improve the
quality of the prints
already developed
Fingerprint Reagents and Targets
from http://www.ridgesandfurrows.homestead.com/latent_print_development.html
Fingerprint Development techniques
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Amido Black: Proteins: Blue-black: Also Commassie blue
DFO (1,8-diazafluoren-9-one): Proteins: Fluorescent Red- A more sensitive Ninhydrin
analogue
Fluorescence examination: naturally occurring chemicals and contaminants: Fluoresce
without treatment with laser sensitive dyes.
Gentian violet or crystal violet: fatty acid: purple color- good on sticky side of adhesive tapeToxic- Yellow-orange laser light source (578nm): Alternate- Fuchsin- Green excitation
(500nm)
Iodine:good on both porous and non porous- fuming
Ninhydrin: porous surfaces like cardboard, wallboard, paper, wood: amino acids: purple
color=Ruhemann’s purple. Treatment with Zn chloride and lasers improve sensitivity
Physical Developer: PD, SPD: Sliver based solution : porous surfaces that are wet or have
been wet: sweat: gray to black
Powders: smooth non porous: color depends on choice
Silver nitrate: chlorides in prints:
Small particle reagent : SPR: wet surfaces: molybdenum disulfide in detergent: lipids : gray
deposit. Non porous surfaces.
Sudan Black: non porous oily or greasy surface: lipids: blue black color
Superglue or cyanoacrylate fuming: non porous surfaces: white. May be dusted with powder
or washed with laser sensitive dyes such as Rhodamine G-6
Vacuum metal deposition VMD smooth non porous surfaces: gold or zinc thin film on latent
See www.fbi.gov/hq/lab/fsc/backissu/jan2001/index.htm.
AUTOMATED FINGERPRINT
INDENTIFICATION SYSTEM
• AFIS –The ability to compare a fingerprint
found at the crime scent with a criminal
fingerprint computer data base
• Cold Searches – searching a data base of
several million prints against a single latent
print in about 10 minutes
LATENT PRINTS
• CHANCE
IMPRESSIONS
• REQUIRE
TRANSFER
MEDIUM
• ENVIRONMENT
DEPENDENT
Fingerprint Visualization
• At the Crime Scene
– Dust and Lift (powders; various colors)
– Magnabrush (iron filings and powder)
• In the Laboratory
– Ninhydrin for paper
– Superglue in tank (sometimes at scene)
– Other (physical developer, etc.)
NINHYDRIN EXAMPLE
AFIS HIT EXAMPLE
FINGERPRINT LAB
PART ONE TODAY
A. Black Powder
– 2 different surfaces:
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Smooth glass slide and
tile
B. Magnetic Powder
– 2 different surfaces
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Smooth glass slide and tile
PART TWO
C. Your Inked or pencil
Prints
– What fingerprint
patterns ?
– Enlarged print (at least
one characteristic)
D. Super Glue
– 1 item- glass slide
E. Evidence Sample
• Everyone will get an item to process for fingerprints
using techniques you have learned/ MUST LIFT A
PRINT
• HOWEVER!!! MUST SWAB BOTTLE FOR
SALIVA FIRST (lightly moistened swab)
– Allow swab to dry while you work on item
– When dry package in envelope
– Once swabbed, dry the swab and then place into envelope
and fill out the chain of custody
– Be sure to take notes on the evidence and sketch on the
card.
REMINDERS
• MAKING A LATENT PRINT VISIBLE
• Place some powder in lid, not too much, circular sweeping
motion, just grazing surface
REMINDERS
• LIFTING A LATENT PRINT ONTO A
FINGERPRINT CARD
Fingerprint card glossy side
Don’t forget info on other side!
SOURCES
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Criminalistics/ Chapter 14 / Saferstein
http://www.fbi.gov/hq/lab/org/lpu.htm
http://www.onin.com/fp/
Kendall FG, Rehn BW. 1983. Rapid Method of Super Glue® Fuming
Application for the Development of Latent Fingerprints. Journal of
Forensic Science. 28(3) 777-780.
• Lewis, LA. et al. 2001. Processes involved in the development of
latent fingerprints using the cyanoacrylate fuming method. Journal of
Forensic Science. 46(2): 241-246
• California Dept. Justice/ Physical Evidence bulletin-PEB 16-17
• International Association of Identification
– (IAI)-> http://www.theiai.org