General Study Guide - Ontario Police College

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Latent Fingerprint Development Processes *****PLEASE REFER TO O.P.C. TRAINING MANUAL FOR HEALTH AND SAFETY RECOMMENDATIONS***** Online References – http://www.cbdiai.org/Reagents/main.html (Chesapeake Bay Division, IAI), www.redwop.com (Technical notes), http://www.rcmpgrc.gc.ca/firs-srij/recipe-recette-eng.htm (RCMP Forensic Identification Services) Porous Surfaces*** – Proper Development Sequence and Types of Chemical Processes (depending on the circumstances not all processes may apply).** All processes, however, are post visual and examination of inherent fluorescence by laser or alternate light source including UV. Development Techniques and ‘Basics’ of Processing Procedure Latent Print Development Colour Ridge Detail Visualized By Method to Record 1. Iodine Fuming* Requires fuming chamber, ceramic or glass dish and heat source. Non-destructive technique Iodine fumes are more senstive to different latent residues than other methods. Clear to dark brown, often yellowishcoloured prints. Physical process by which Iodine vapours are absorbed by the fatty & oily components of print residue. Photograph at the greatest intensity of colour change. Developed prints tend to fade quickly. 2. DFO (1,8-Diazafluoren-9-one) (1988) Specimen can be dipped or sprayed Must be dryed & placed in 100C (212F) oven for 10- 20 minutes. Sometimes pink prints are visible. /Yellow fluorescence. Chemical reaction with amino acids & eccrine components of print residue &/or laser &/or F.L.S. @ 450,485,525,530 nm using orange goggles for white paper or laser or F.L.S. @ 570-590nm and red goggles for manilla envelopes, brown paper bags and cardboard. Illuminate with F.L.S. and photograph with orange or red camera filter. 3. Ninhydrin Solution can be applied by dipping, spraying or painting. Specimen must be dryed and then heat and humidity (set @ 60-70%) can be applied to accelerate development of prints. Replaced Silver Nitrate (reacts with salt) process Magenta to deep purple. Chemical reaction with amino acids and proteins in eccrine components of print residue. Purple coloured compound produced known as ‘Ruhemann’s Purple’. Zinc chloride may be used to fluoresce, and enhance, the ninhydrin developed ridge detail. Photograph with a green filter.
4. Silver Physical Developer (Ag-PD) (1975) Pre-wash with maleic acid (10 min. or until bubbles disappear.) Specimen is immersed up to 20 min. & item s/b agitated (gentle rocking motion). Post-wash in 3 separate distilled water baths for ~ 5 min. each before re-processing. Grey Chemical reaction with lipids, fats, oils and waxes in print residue. At present, no reagent has been as successful as the Ag-PD for visualizing the water-insoluable components of latent print residue (fats and oils/lipids, proteins) on paper. Photograph. * In their classes, the FBI is teaching a new method of using iodine. By mixing it with solvents and spraying it on papered or painted walls or paper documents, latent prints are being developed which last several hours. Therefore, photography of latent prints developed using Liquid Iodine need not be immediate. This method of spraying Liquid Iodine can be used at crime scenes if protective measures are taken. Iodine fumes are toxic & corrosive. Every precaution should be taken to avoid inhaling iodine fumes. A full-face, self contained breathing apparatus and protective clothing such as coveralls and gloves must be worn. CAUTION: The mixing and spraying of this solution must be done in a fume hood or while using a full-face breathing apparatus. ** Physical Developer (used immediately after item has been dryed and fluorescence examination) is especially successful in developing latent prints on porous substrates that were previously wet. (Refer to Figure 5.8, pg.187, A.F.T. Flowchart for fingerprint visualization on paper and cardboard.) Sodium hypochlorite can also be used post-PD on porous, previously wet items. PD also works well on clay fire bricks, concrete, latex or rubber gloves, both sides of adhesive tape, rayon or nylon clothing, unfinished porcelain, unfinished wood and wooden knife handles. ***Thermal and Carbonless Papers are used for many current business applications and therefore “a fundamental understanding of its chemical and physical properties is required to assist the examiner in deciding what possible method of chemical processing will not damage these specialty papers, while subsequently allowing for the development of quality friction ridge detail on their surface.” (Jon T. Stimac, Journal of Forensic Identification, Vol.53, Issue 2, 2003) Refer to separate article on Latent Print development on Thermal Paper in this study guide.
Page 1 and 2: What to Study (Information from Ont
Page 3 and 4: evidence evidence for further exam
Page 5 and 6: h. Use alternate lighting sources a
Page 7 and 8: History of Fingerprint Identificati
Page 9 and 10: Harris Hawthorne Wilder, Ph.D. (191
Page 11 and 12: Friction Skin Structure Skin is one
Page 13 and 14: Friction Skin - Dermal Papillae The
Page 15: E- Evaluation: It is not sufficient
Page 19 and 20: Metallic powders - consist of very
Page 21 and 22: Post-Cyanoacrylate Dye Stains Ardro
Page 23 and 24: 3. Modified Physical Developer (MMD
Page 25 and 26: Leucomalachite Green (RCMP) extrem
Page 27 and 28: Additional Latent Print Development
Page 29 and 30: Developing Latent Prints on Tape -
Page 31 and 32: Development of Latent Prints on The
Page 33 and 34: Manual of use Due to the sensitivit
Page 35 and 36: Reagent Reacts With Type of substra
Page 37 and 38: SUBSTRATES AND SUGGESTED LATENT IMP
Page 39 and 40: Waxed cardboard (e.g. milk cartons,
Page 41 and 42: Examining the Crime Scene (O.P.C. T
Page 43 and 44: The only exception is paper exhibit
Page 45 and 46: Very approximate correlations betwe
Page 47 and 48: Procedures for conducting an examin
Page 49 and 50: For use on CA-treated prints, the l
Page 51: Alternate Light Source Reference Ch

General Study Guide - Ontario Police College

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