IMPORTANCE OF FINGERPRINTS Positive identification of the

IMPORTANCE OF FINGERPRINTS • Positive identification of the offender • Prove presence at the scene – Victim, witnesses, and suspect • • Frequently found at scenes Useful in interviews of suspects Relatively easy to process with limited equipment Do not change from womb to grave

CLASSIFICATION • Formula (alpha-numeric) given to all 10 fingers on a fingerprint card based on – – Pattern type Ridge count Ridge tracing i. e. 15 O 9 R OOM 17 U OOO • Pattern areas (loops/whorls) consist of cores, deltas, and ridges • Filing system for retrieval

FINGERPRINT IDENTIFICATION • Friction ridges on fingers, thumbs, palms – Feet included (toes and bottom of feet) • Compare with lifts at scene and 10 print cards

FINGERPRINT IDENTIFICATION • Points are identified – no set number to make ID – – Bifurcation – ridge forks becomes two or more Islands – bifurcates then forks into ridge Ending ridges and dots – just that Short ridge – no longer than width of corresponding ridges – Divergence – spreading apart of two parallel ridges

VISIBLE IMPRESSIONS • Visible – finger coated with foreign material transferred to a clean object – “Dust” prints coated in dust – “Patent” prints coated in oil, blood, etc. – Visible w/o processing or light – Difficult to lift – photograph, electrostatic dust lifter

PLASTIC IMPRESSIONS • Result of fingers pressed into a soft surface, putty, wet paint, soap, grease, recently painted surfaces, adhesive tape, etc. • Difficult to lift, photograph and lift by microsil, dental stone, other molding type material

LATENT IMPRESSIONS • Reproduction of friction ridges transferred to any surface touched • 98% water; and other acids, fats/oils, and salts • Hidden, need to be developed to discover – Powders and/or chemicals • Oblique lighting can sometimes help but not always the case – processing is best

CONDITIONS THAT AFFECT LATENT IMPRESSIONS • • • Manner it was transferred (gloves, etc. ) Nature and quality of substance Weather conditions Physical or occupational defects of person Condensation and heat

POWDER PROCESSING FOR LATENT IMPRESSIONS • Primarily used on non-porous surfaces • If blood, hair, or other items adheres to the object, collect the item and submit to the lab • Black or gray powders preferred • If item is wet allow to dry naturally then apply powders – do not use heat sources • If too much powder used, lift the excess powder and lightly reapply then lift

APPLICATION OF POWDER • Use powder sparingly – lightly distribute the powder across the print until the ridge details become visible • Use short quick strokes or twirl • Lightly brush away excess powder – don’t blow on the print • Ready to lift and/or photograph the print

LIFTING THE PRINT • Enough lifting tape to cover the print • Press sticky side over the prints and smooth out to prevent air bubbles • Gently peel from one end, place on a card • Put ID data on card – Location of offense, date, case nr, offense, lifter’s name, good description of where the lift was obtained

CYANOACRYLATE PROCESSING • Non-porous (hard) surfaces • Fuming chamber (fish tank/aquarium) • 3 -4 drops “super glue” on tinfoil – 1/2 drop of sodium hydroxide to glue – cup warmer inside – Heat lamp outside • Fumes adhere to prints then harden into a white color – dust and lift – can be done several times VENTILATE

CHEMICAL PROCESSING • Three primary chemicals: – Iodine – fats/oils – Ninhydrin – acids – Silver nitrate – salts • Can use all three on porous items but in the above order I-N-S • Need to photograph to record/capture • Caution – chemicals can cause injury and respiratory distress - ventilate

IODINE PROCESSING • Iodine crystals when exposed to slight heat will vaporize producing violet fumes which adhere to fats/oils • Fuming gun, chamber with crystals, plastic bag with crystals (shake and bake) • Prints appear yellowish/brown; photograph when appear as they will fade over time

NINHYDRIN • • Dye that reacts to amino acids Aerosol cans preferred May cause inks to run – test similar item Spray object thoroughly – beginning after one hour to 24 hours purple prints appear • Photograph with green filter before fading • Heat (iron with steam over the object) will speed up the process

SILVER NITRATE • Crystals mixed with alcohol or water • Reacts to salts when immersed and blotted dry • Appear reddish brown when exposed to light and item will turned black quickly – Remove from light as soon as prints appear • Photograph quickly and store in dark area

OTHER CHEMICALS • • • Sticky-side powder for adhesive tapes Gentian violet for adhesive tapes Amido black to enhance blood prints Small particle regent for wet surfaces Smoke technique - camphor Silver plating

LASERS AND ALTERNATE LIGHT SOURCES • Two different things • Use either before any other methods attempted • Fluorescent powders may be used • Special eyewear or flashlight lens needed to visualize the wave lengths and results (also to protect the eyes from injury)

AFIS • Automated Fingerprint Identification System – computer scans the print comparing it to the data base – Class B misdemeanors and above – No palms or little fingers (#5 and #10) in TX • Takes time to enter – examiner must identify the points prior to entry • Once entered scans continuously – may take years to get result as suspect was not previously arrested

TEN PRINTS PREPARATION • FBI/DPS cards • Visually inspect for problems – Disabilities – try best as possible – fresh cuts – allow to heal first – excessive perspiration – dry hands • Ink plate, printers ink, cardholder, roller • Thin coating of ink

TEN PRINT PROCEDURES • • • Roll thumbs to center of body Roll fingers from center of body Roll all of them from edge to edge Try to get the tip to below the first joint Then all four fingers simultaneously and thumbs (this verifies correct order of individual prints)

PALM PRINT PROCEDURES • DPS/FBI/Local palm cards • Use roller to ink entire palm to wrist and edges of palm • Use an aerosol can or cut piece of cardboard tubing • Roll palm onto card over the tubing/can • Many times palms are found more often at scenes than fingers – examiners love palms