Lecture 13 Fingerprints

1. Lecture 13Fingerprints On-Scene Considerations

2. Types of Fingerprints Latent Prints Patent Prints Smudged Plastic Prints Invisible Visible Malleable Surface Chewing gum Wet soap Candy Treatments to Visualize Enhancement Generally Surface Dependent

3. Types of Fingerprints Patent Prints Positive Transfer Prints of the Ridges Contamination Blood Dust Soot Oils

4. Patent printsPrints in Dust • Capturing prints in dust • Lift dust with gel or electrostatic lifter • removes some of the material leaving a void which is visible • Question – if a finger is pressed onto a dusty surface and lifted using a gel or electrostatic lifter, what is lifted and what remains?

5. Types of Fingerprints Plastic Prints • Fresh print • Substances that melt easily or soften • Chocolate • Adhesive tape • Thick layers of dust • Plastic explosives • Putty • Candle/sealing wax • Fats/flour/soap/sticky oily films/tar/pitch/clay Negative Transfer Prints of the Grooves WHY?

6. Plastic printsA type of Patent print • Negative impression of ridge formation • Results from contact of finger with soft substance • Clay, fresh paint • Ridges impressed into surface • Creates negative impression of the ridges • Ridges are deeper than surrounding area • Photograph with oblique lighting & close-up lens before further processing • Cast of impression can be made @ lab • First spray with release agent • Cast impression with silicone casting material: Mikrosil • Cast can be made at scene Cast Print from Soap

7. Plastic Print Finger Presses into Chewing gum + Groove of Fingerprint Ridge of Fingerprint Negative Print Chewing Gum Presses into Soft Gum Not Pressed into Soft Gum

8. Latent Prints Invisible Prints • Found on non-porous & porous surfaces • Smooth or textured surfaces • Paper • Fabrics • Metals • Plastics • Visible only after development

9. Latent Prints Latent Prints Fingers Covered with small amount of grease/sweat/dirt transferred to surface as a ridge impression Positive Transfer Contamination Blood Dust Soot Oils WHY? What is the difference between a Latent & Patent Prints?

10. ExemplarsInked/Digital Prints from Known Persons • Digitized Scans from Glass • Inked Impressions • person’s fingers & thumbs in ink and then pressed onto a fingerprint card • Toes & soles of feet also yield prints • Palm prints can be valuable • Fingerprint cards can be classified • Manually • Modified Henry System • Other classification systems • Semi-automatically • AFIS/IAFIS

11. Information from Fingerprints • Time print had been on surface? • No – not reliably • Check when surface last cleaned • Method had to have removed existing fingerprints • Sex, race or occupation? • No – not reliably • IR imaging • Fatty Acid analysis • Drugs

12. Classifying Fingerprints

13. Classifying Fingerprints HistoricallyThe Henry System • Odd-numbered fingers count for the numerator. • Even-numbered fingers count for the denominator. • If a whorl appears on a finger, the value in the box is added to either the numerator or the denominator. • The primary classification is calculated using these values and then adding 1 to both numerator and denominator. • The values for the primary classification may then range from 1/1 (zero whorls) to 32/32 (10 whorls).

14. Comparing Latent FingerprintsWith Exemplars

15. Fingerprint IdentificationThe Basis of Comparison

16. Fingerprint ClassificationAFIS • Searches millions of records in relatively short time. • Provides a list of possible matches • Still need a person to make the final ID • Manually compares • 10 best matches

17. AFIS How It Works

18. Environment Weather conditions Sweat glands more active in warm weather Heat Humidity Freeze-thaw cycles Fragmented by condensing moisture Fingerprint Quality at the Scene Deposition Mechanism and Other Factors • Nature and cleanliness of surface • Amount of contaminant • Pressure applied • Movement during transfer • Condition of the friction ridge detail

19. Finding Fingerprints at the Scene • Latent and patent fingerprints can be anywhere and everywhere. • The problem is locating those that are latent and then developing them. • Transportable evidence with fingerprints should be taken to the latent print laboratory. • Some prints need to be developed @ the scene • Creates the problem of finding fingerprints with probative value. • Scene dictates where to find probative fingerprints. Waste of time to. memorize the list … most important items there are the last two points on the right : • Use your imagination • Be the burglar (perpetrator). This is when a search for probative prints pays off. Search is an intellectual exercise. The thought process might go something like, “What would I touch if I were the scumbag who did this?

20. Fingerprints occur in three forms: • latent (invisible), • patent (visible) and • impression or plastic • Sub-category of patent prints • Ridge detail impressed into a malleable material is visible. • Smudged prints • Sub-category of latent and patent prints, • Little or no discernible friction ridge detail. • DNA from smudged prints … will be increasingly important as investigative tool. • Developing • What method should be used? • Physical techniques as simple as powder dusting • Complex chemical treatment, such as superglue fuming or lanthanide chemistry. • A special light source that causes the fingerprint residue to fluorescence; • Argon or Hd:YAG laser (2) or an Alternate Light Source (ALS).

21. Fingerprint Components Goal: Obtain as many prints as possible Mostly Water Soluble Substances Latent Print Mostly Water Insoluble Substances • Water Insoluble Substances: Fat, Oils • Water Soluble • Water resistant: proteins, urea, lipoproteins • Trapped water soluble: amino acids, proteins, salts, etc Both Water Soluble And Insoluble Substances

22. Eccrine Sweat Inorganics • Sodium: 34-266 mEq/l • Potassium: 4.9-8.8 • Calcium: 3.4 • Iron: 1-70 mg/L • Chloride: 0.52-7 mg/mL Organic • Amino acids:0.3-2.59 mg/L • Proteins: 15-25 mg/dL • Glucose: 0.2-0.5 • Lactate: 30-40 mM • Urea: 10-15 • Pyruvate: 0.2-1.6 Miscellaneous • Fatty Acids 0.01-0.1 ug/mL • Sterols: 0.01-0.12 • Enzymes • Immunoglobins • Fluoride • Bromide • Iodide • Bicarbonate • Phosphate • Sulfate • Ammonia • Magnesium • Zinc • Copper

23. Sebaceous Sweat Secretions OrganicS • Triglycerides30-40% • Free fatty acids15-25% • Saturated - 50 • Monounsaturated - 48 • Polyunsaturated - 2 • Wax esters20-25% • Squalene 10-12% • Cholesterol 1-3% • Cholesterol esters 2-3% Trace organics • Aldehydes • Ketones • Amines • Amides • Alkanes • Alkenes • Alcohols • Phospholipids • Pyrroles • Pyridines • Piperidenes • Pyrazines • Furans • Haloalkanes • Mercaptans • Sulfides

24. Anatomical VariationAfter 12 hr Accumulation Site Total Lipid CH CE TG DG FA WE SQ TG+DG+FA Forehead 288 1.1 2.7 29.6 3.5 27.2 25.9 10.1 60.3 Cheek 144 1.1 3.4 39.4 2.7 15.4 26.9 11.2 57.5 Chest 122 29.7 24.9 25.7 10.3 60.0 Back 84 57.8 Arm 76 55.1 Side 57 56.6 Leg 57 56.3

25. Preserving Fingerprints • Print types that populate scenes can unleash a cascade of developmental choices, many of which can be confusing to a student or a novice investigator. • Patent print May require nothing more than photography followed by a lifting method. • Partial print Requires well thought out strategy for enhancing what is visible and what is not (the latent part of the print). • If the print is plastic, that is, impressed into a soft surface, the best method might be to cast it using a silicone-based material. • Resulting cast can be enhanced in the laboratory. • If the evidence is transportable, techniques are available in the laboratory that might be better suited because the conditions there are controlled.

26. Preserving Patent Fingerprints • One investigator has written that photography of patent and plastic prints is sufficient to capture the detail necessary to make comparisons, • Of the three types of fingerprints, visible (patent) fingerprints can be photographed directly. • Impression fingerprints can usually be photographed under special lighting conditions. • Only the latent fingerprints are difficult to photograph. They must first be made visible. • Following that advice could lead to failure. • Patent prints exist: Contamination from an exogenous source, such as blood, oils, cosmetics, etc. • Photographing as sole means of archiving patent prints captures only that which is visible. What is missed, is invisible. • It is critical to understand that patent prints can have a latent component. • Enhancing these should include a well thought out strategy designed to enhance all potential ridge detail present in the deposited fingerprint. • Knowing how to develop fingerprints … requires understanding chemistry of fingerprint reside. This means understanding the origin of the fingerprint residue.

27. Origin of Fingerprints • Print Residue: mixture of secretions • Sweat glands, skin cells, exogenous contaminants – blood, oils, cosmetics, etc. • Although seems simple - because the components of glandular secretions are known - it is complicated. • Sweat glands not all present on fingers or feet … friction ridge skin. • Generally, fingerprint residue contains primarily water soluble and/or insoluble substances.

28. Sudiferous glands Secrete directly onto the friction ridge skin • Apocrine & Merocrine Sweat Glands • Both Have myoepithelial cells • Contract & squeeze • Causing discharges, left on the surface of the skin.

29. Apocrine Glands Merocrine gland • Eccrinesweat glands: throughout the body … more numerous than apocrine glands. • Approximately three million Eccrine glands … • Most numerous on the palms and soles - approximately (3000 glands per square inch. • Densities range from 60 per cm2 on the thigh to 350 per cm on the forehead. • Coiled structures lying deep within the second dermal layer of the skin, the dermis. • Empties onto the skin surface, • Specifically on the epidermal ridges of the friction ridge skin. • Not associated with hair follicles. • Responds to elevated body temperature due environmental heat or physical exercise • Produces profuse sweating on hot days or when physically active • Noticeable on palms and soles when emotionally stressed. • Secretions have forensic value with respect to fingerprint development. • Scent glands that respond to emotional stress. • Begin functioning at puberty and produce moisture during emotional experiences - when someone is upset, frightened, or experiences pain. • Active when a person is sexually stimulated. … most numerous in the armpits (axillae), groin associated with hair follicles and in the regions around the nipples (areoles). … • Not historically forensically important, especially with respect to locating latent fingerprints at the crime scene. • These secretions are a viscous and cloudy and potentially acted on by bacteria to produce a noticeable odor. • Location suggests a potential forensic role in sexual assault investigations.

30. Holocrine Gland - Sebaceous Gland: • Secretions are oily substances from broken cells known as sebaceous cells, • Produce globules of a fatty material that accumulate inside the cell causing them to swell and burst. • The resulting mixture of fatty material and cellular debris on the skin is called "sebum," • Found on all areas of the skin EXCEPT the friction ridge skin. • Sebum most prominent on the forehead and areas where there is hair. • Secretions … eccrine, apocrine and sebaceous glands form the fingerprint residue left at the crime scene.

31. Sweat Gland Summary • Each gland is located such that it does not occur in the same locations on the body. Unlike eccrine glands, sebaceous glands are not found on the friction ridge detail skin – palmer regions of the hands, feet, fingertips, toes. • Sebaceous glands … Sebaceous contributions to fingerprints occur when an individual touches regions of the skin where these glands are plentiful, e.g., head, cheeks, forehead, etc. • Apocrine glands … not secrete as much material as the other two, and while they are located on all areas of the body, they are most prominently associated with hair follicles in the groin. Importantly, both sebaceous and apocrine glands are associated with hair follicles but eccrine glands are not. • Eccrine glands located on all regions of the body … plentiful on the friction ridge skin – hands, palms and soles of the feet … Always contribute to the fingerprint residue. From a practical perspective, apocrine secretions contribute to the print residue only if someone touches the groin area.

32. Fingerprint Residue • Each gland can contribute to the overall chemistry of residue • Depends on the habits, stress level and physical exertion of the person leaving the print. • Continually runs fingers through his scalp or habitually touches his face or forehead, … prints should have an abundance of sebaceous secretions. • Continually washing, his prints might be cleaner, that is, they should have a relatively smaller amount of sebaceous oils. • Sexual assault, • Assailant touches his or the victim’s groin region … subsequently touches something at the scene, say, a knife, the • Residue on the handle of the knife should have an elevated level of apocrine secretions relative to those from eccrine and sebaceous glands.

33. Fingerprint Development • Experienced investigators recognize that the surface type dictates their approach to developing fingerprints on-scene as well as in the laboratory. They employ techniques that work the best on certain surface types. General considerations a logic-based decision process is suggested as a effective approach for developing fingerprints. • Some authors of crime scene investigation texts barely treat the subject: Henry Lee et. al. write the following. • “Physical methods are used for any dry, non-porous surfaces like glass or plastic.” • For dry and wet surfaces, they write, • “Chemical processing methods for latent fingerprints can be used on dry and wet surfaces.” • For latent prints on porous surfaces they caution, • “Latent prints on porous surfaces are visualized by the use of chemical methods. Because of the nature of the surface and the fact that the friction ridge secretions are dissolved into the surface, the chemical method chosen for visualization must react with the secretions and not the surface.”

34. Fingerprint Development • Fisher considers each surface but instead of considering them as distinct topics, he covers them broadly as entry-level discussions related to specific developing techniques • Gardner goes into more detail and depth than either Lee or Fisher, considering surfaces and the characteristics for porous surfaces, nonporous smooth and rough surfaces and special surfaces. • Fish et al. discuss surfaces much like Fisher but adds a reference chart of techniques published by the Chesapeake Bay Division of the International Association of Identification to guide investigators. They do not explain, however, how to use the techniques or the caveats involved with each. • The Chesapeake Bay Division of the IAI website lists reagents for use on various surface types: Porous, non-porous, glass, plastic, wet, post-cyanoacrylate, metal, adhesive tape, glossy paper, cartridge cases, raw wood, post-Ninhydrin, and UV induced. • The website has links to the specific techniques. Each method considers the pitfalls and formulations for the techniques and safety concerns.

35. Fingerprint Development • Fingerprint textbooks – Champod, et. Al.; Lee and Gaensslen discuss surfaces and compatible techniques in detail. • The most comprehensive compilation of development techniques is published by The British Home Office (Home Office Scientific Development Branch – HOSDB), whose manual titled, Manual of Fingerprint Identification Development Techniques covers fingerprint development techniques and surfaces for which they are compatible. The manual presents workable schematics – cascades - for employing various techniques in sequence. • Charts outline a sequential approach to print development, including primary, special, and secondary routes of analysis. • Still, the British approach is surface-based, which is clear from the following quote. • “The surface on which fingerprints are to be developed should normally determine the sequence of processes to be used, except for fingerprints contaminated with blood...” • Students and novice investigators … choosing specific development method for specific application can be confounding, especially if there are significant resources available.

36. Aging of Fingerprints

37. SurfacesPorous Water sol. Deposits (WSD) absorbed within seconds Water evaporates over time Leaves mixture of residues behind Amino acids Stabilize Minimal migration < 80% RH Urea & chlorides Migrate continuously Slower @ RH < 80% minimal @ first week Penetration into substrate depends on relative Humidity (RH) Older prints have significant diffusion of urea & chlorides Blurred images w/respect to these components Water Insoluble Substances Amino Acids Migration slowed by Paper Diffusion Urea, salts, etc

38. Paper evidence Porous Surfaces • Can pinpoint terrorist activities, forgeries and/or provide investigative information in major crime investigations. Critical vehicle leading to a successful prosecution. • Paper defined as a porous surface & is usually treated as porous for developing latent prints. • However, there are caveats to this approach. • Porous surfaces absorb fingerprint residue. Because of that, they must be treated differently than nonporous or non-absorbent ones. • The issue is that papers absorb fingerprint residue to varying degrees and amounts, • Determined by the paper’s absorption characteristics as well as humidity, temperature and the environment. • For this reason, porous surfaces can be classified into groups based on how quickly they absorb print residue. • Some papers are considered “hard” and often have a glossy sheen. • They typically do not absorb fingerprint residue readily or quickly. … glitzy magazine cover, • Choice of fingerprint development method different than for highly absorptive paper where residue penetrates easily and quickly.

39. Research on Porous surfaces • Depth and shape of the fingerprint residue penetrating the porous material. 15 types of paper and the diffusion of amino acids present in the fingerprint residue. • Goal to understand how residue penetration varied with porosity, smoothness and density of the paper versus quality of the developed prints. • Penetration varied considerably from paper-to-paper – least penetration to most - according to the following progression: brown wrapping paper, smooth copier paper, the inner side of an envelope, writing paper, copier, outer side of an envelope, cotton paper and postcard board. • Inverse relationship between penetration and the smoothness of the paper • Direct relationship with porosity. • Best quality was obtained when the print residue penetrated the porous matrix to a depth of between 40-60 microns. • 40 microns = .00157480315 inches • Very shallow and very deep penetrations correlated with poorer quality prints. • Looking at only the amino acids which are water soluble substances. They did not examine the oily sebaceous secretions of the residue.

40. Implications of the Research • Changed then existing paradigm of how to think about developing latent prints on porous surfaces. • Divided porous surfaces into two broad categories, • Smooth, relatively non-absorbent papers: • Development techniques compatible with non-porous surfaces. • Highly absorbent papers foster deeper penetration: • A development strategy for developing the Eccrine print components, e.g., amino acids.

41. Print Development Cascades • Development methods done a specific sequence such that each step will not affect print development with subsequent steps. • Can be stopped at any time • Cannot go backward in the cascade Step 1 Technique 1 Step 2 Technique 1 Step 3 Technique 2 Step 4 Prints developed Prints developed Prints developed Prints developed

43. Nonporous Surfaces • At most crime scenes non-porous surfaces are the most plentiful, • Makes them important candidates for developing latent fingerprints at crimes scenes: burglaries, homicides, sexual assaults, stolen vehicles, etc. • Research for new methods for developing fingerprints … dizzying array of techniques … the choice can be confusing for students, novice investigators and experienced scene investigators. • What happens to prints on nonporous surfaces? • The most important is what happens as the print ages.

44. Aging of Latent PrintsNon-porous Surfaces Emulsion Of Water Soluble & insoluble Substances Nonporous Surface Dehydration Over Time Nonporous Surface Oxidation of Oils Days-Weeks-Months After Deposition

45. Drying Fingerprint Emulsion • Fingerprint residue dehydrates over time … quick or slow depending on the surface characteristics & environment. • Emulsion eventually dries • Nonreactive chemicals • Print residue emulsion stabilized by the glycerides present. • Dry emulsion: Water phase no longer present • Changes the chemical environment of the print residue. • The residue present but is no longer an emulsion. • Can rehydrate emulsion using acetic acid or ammonia vapors • Other effects … oxidation, pollution, dust, etc, … affect the fingerprint residue and gives development problems.

46. Print emulsion disrupted • Temperature • Humidity • Air currents • Exposure to sun • Nature of surface Drying • What Happens? • Print Dries • Loss of stickiness • Narrowing of print ridges • Loss of continuity along print ridges • Clarity Affected by • Dust • Pollution • Bacterial action • Oxidation • Emulsion decomposition • Diffusion into surface Print Clarity

47. Avg. Lifetime of Sweaty vs. Greasy Latent Prints on Nonporous Surfaces Outdoors (days) Indoors (weeks)

48. Developing Fingerprints on Nonporous SurfacesCascades

49. A Nonporous (Hard Surface)Development Cascade Dry Surface Wet Surface Optical Detection Optical Detection Dusting Lanthanide Superglue Fuming Small Particle Reagent Reflective mode CTF - Solid- State Acquisit. Vacuum Metal Deposit Reflective mode Observation & recording In luminescence mode Reflective mode Reflective = examining with ALS or flashlight in oblique mode Luminescence = examining with ALS in fluorescence mode