Impression Evidence

1. Impression Evidence General & Scene Considerations

2. Overview Impression Evidence Anything that leaves an impression can be compared with an original • Class Characteristics • Marks produced during manufacture AND during routine use • Made during the manufacture of the tool or the object • Accidental or Unique Characteristics • Small (or microscopic) unique (accidental) marks are thought to be traceable to a specific object • Occur during normal useage

3. Classifying Footwear Impressions • Three categories: • Visible: Occur after someone steps into a foreign substance and then transfers the substance to a clean surface. • Depending upon the background color, a visible print may be a simple impression made from dust on the sole of the shoe. • Plastic: Occur when someone steps into a malleable (soft) surface and leaves a three-dimensional impression. • Typically, this could be an impression in mud or cement. • Latent:Those that are invisible to the naked eye and typically require an aided eye to make them visible.

4. General Characteristics of Impression Evidence • 2D Impressions • Defined as a pattern lying ON TOP of a surface • Latent (invisible) • Patent (visible). Examples are fingerprints, footwear impressions and tire tracks, among others. • Dust impressions are usually classified or defined as 2D impressions, • Actually three dimensional having very shallow depth and surface topology

5. 3D impressions • Object impresses its pattern into a softer surface, • When tire makes pattern in wet mud. • The famous impression of Neil Armstrong’s footwear impression on the moon is an example of a 3D impression

6. Impression Evidence • Large, diverse group, • Expect at least one category present at most scenes. • Fingerprints – most prevalent • Next would be footwear and tire impressions • Bite marks (sexual assaults), lip prints and ear prints comprise another category but occur much less frequently. • Tool mark impressions is another large class of impression evidence that comprises several subcategories: • Screw drivers, saws, cutting tools (wire cutters) etc. • Ballistics evidence: • Bullet impressions, • Cartridge case impressions, and marks made by other

7. Categories of Impression Evidence Fingerprints Footwear Prints Tire Tracks Tool Marks Bullet Marks Cartridge Cases Fired Weapon Bite Marks Ear Prints • Impressed prints • Shape of a tool • Striated impressions or striated marks/scraping marks • Scrapping of tool’s surface against receiving surface

8. Footwear Impression Evidence

9. A Class of Associative Evidence • Refers to its future use; to help ascertain the truth of alleged facts. • Footwear evidence = Associative evidence. • Helps investigators (police and prosecutors) and juries support contention that someone had been at crime scene. • Can identify which shoe left an impression ,,, can help place someone at the scene. …. • Alone, not determinative of guilt, • Help circumstantially toward that end. • Thus finding footwear evidence linked to an individual shoe can be critical evidence, • Used by a prosecutor during trial. • Also helpful for investigators to understand the veracity of witness or a suspect’s statements. • Locating footwear evidence: not easy … logic can point to the location where to search. • Time and effort spent locating, photographing, lifting and comparing impression evidence is critically important.

10. National Research Council 2009 Report • National Research Council of the National Academy of Sciences suggests that pattern (impression) evidence should be interpreted more carefully. • The report says that additional research is necessary in order to determine the underlying scientific basis of pattern evidence comparisons. • NRC committee also suggested there should be a statistical basis for making these comparisons, which currently, does not exist. • Practitioners do not universally agree that a statistical basis is necessary for making valid comparisons. • The NRC report does not say or imply that footwear comparisons are not valid nor does it say or imply that these comparisons have no forensic value.

11. Value of Impression Evidence Laboratory Examinations Establish Links Links to Other Crimes • Database searching • Footwear impressions from various crimes • Useful for investigations of repetitive crimes • Burglaries • Recidivism rate is high >50% • Multiple impressions • Absence of multiple impressions • Suggests a lone perpetrator Minimum # of Perpetrators • Backtracking footwear impressions • Path of perpetrator • Discarded weapons or other evidence • Associate footwear with tire impression - lead to a vehicle Association with Other Evidence

12. Entering a House • From the Outside • Defines residue type on shoe. • Subsequent steps transfers residue from shoe to carpet. • Forensic value not known until found and evaluated. • Example • Burglar enters a house through a window and steps onto a carpet, • What is probability that dirt residue from sole will leave an impression? Entry Point 1 Entry Point 2

13. Hypothetical Murder Scene • Assume two burglars enter scene at different points, • Expect different footprints • ‘Entry Points ‘1’ and ‘2’. • If both footprints entering house at different locations had the same sole pattern (class characteristics) • Suggests @ least two people involved. • Remote possibility that same person entered on separate occasions. • Close examination of the size and other characteristics might dispel that argument. • Using the same logic, suppose a third unknown fingerprint was found inside the house. • Suggests a third perpetrator.

14. Impression Evidence is Commonly Overlooked

15. Why Impression Evidence IsOverlooked or Not Found • 1. Not aggressively looking for • Belief can’t be found • Incomplete understanding of value • 2. Incomplete search of scene • Inability to find points of exit/entrance • 3. Lack of Understanding a Class of Fragile Evidence • 4. Lack of knowledge of How to Collect and Preserve Training 1. Weather Obliterates Outside Prints 2. Surface Characteristics not Conducive to Production of Impression Evidence 3. Scene Entrance Only Access to Scene Scene 1. Initial Scene Responder Obliterates 2. Public Obliterates Before Authorities Arrive Other

16. 2D ImpressionsCommon but Overlooked

17. Types of 2D Impressions Wet Residue Impressions Dry Residue Impressions Made from Dust Made from a Wet Slurry

18. 2-D Impressions • Most found on floor surfaces • Magazines/newspapers, • Tile floors • Dust prints on carpets • Shoe prints on doors • Stepped-in grease/oil/blood • Requires careful inspection/search of scene • A category of fragile evidence • One of the first activities • Impression transfers vary • Clean shoes leave impressions on paper/glass/countertops/furniture • Dirt and/or dust • Wet grass • Grease, oil, wax or furniture polish • Blood or other fluids. • Visibility of an impression • Contaminating material deposited by shoe • How it contrasts w/a surface • All impressions are potentially identifiable • Often, less visible impressions leave more detail

19. Intellectual On-Scene Impression Evidence Checklist • ALWAYS Expect Impression Evidence. • Study the Scene!!!!! • What is the likelihood of finding probative impressions? • Where would they likely be? • Are they wet or dry residue impressions • Would they be plastic, latent, visible? • What is the strategy for archiving? • Is it necessary to enhance them? • Can they be lifted? • How should they be preserved?

20. Impression Prints @ Crime Scenes Spilled Blood Victim’s Clothing Point of Occurrence Furniture Floors Strewn reading material Areas of Struggle Windows Adjacent areas outside Point of Entry/Egress Struggle-to-Victim to Exit Point Path Through Scene On Doors – kicked in Other Footwear Patterns Landscaping Driveways Walkways Outside

21. Likelihood of Detecting 2D Footwear Patterns

22. Following Footprints Through the Scene Bodziak: Footwear Impression Evidence, 2nd Ed, CRC Press, New York

23. Using Technology

24. Finding Footwear Impressions2D Impressions Flashlight – Oblique Lighting Mirror Natural Light Infrared Ultraviolet Short & Long Wave RUVIS ALS

26. The Mirror Technique

27. Enhancing & Archiving Impressions

28. Composition of Dust and Soil • Dust – General Considerations: • General term for solid particles with diameters less than 500 micrometers • Comes from the atmosphere – sources include: • soil dust lifted up by wind, • pollution, • volcanic eruptions, • animals and • people.

29. House Dust • Human environment, e.g., • Homes, offices, etc., • Contain human skin cells, bacteria, plant pollen, human and animal hairs, feathers, textile fibers, paper fibers, minerals from outdoor soil, • Other materials, • All come from the local habitat. • The quantity and composition of house dust varies greatly with seasonal and environmental factors: • Surroundings, • exchange of outside air, • age of the house, • building materials and their condition • quantity of furniture and carpets, • state of preservation. • ventilation, • heating/cooling systems and • habits of those living in the house.

30. House Dust • House dust consists of inorganic (minerals) and organic matter, • Relative proportions vary considerably. • Dust from the homes with animals consists nearly completely of organic material. • In a study of 318 house samples, the proportion of organic matter ranged between <5% to >95%. • A survey of 11 homes showed • Organic content of house dust ranged between 25.7% to 56.5%, • Floor dust from seven offices had an organic fraction of 33%. • Variances vastly different in different regions – • North, south, east, midwest, southwest, west. • Rural or urban.

31. Enhancing 2D Impressions - Overview The Logic of Enhancing Impression Evidence • Understand the likely content of dust at scene • Archive – Photography • Determine type of Impression • Dry Residue Impressions • Electrostatic Lifter • Gel Lifter (Gellifter) • On paper • Chemistry (iron) • Wet Residue Impressions • Gel Lifter • Chemistry • Fe: Ammonium Thiocyanate • Fe/Mg: 8-hydroxyquinoline • Oils: Iodine/benzoflavone or starch • Dusting • Black magnetic dusting powder • Superglue fuming The current paradigm for enhancing dust impressions at crime scenes is single dimensional … typically involves lifting or chemical tests to visualize the mineral content of the dust. Sort of a crap shoot.

32. Electrostatic Lifting • Apparatus that creates static electricity between dust particles in the impression and a foil-backed Mylar film placed over the impression. If the print lifts, it is a dry residue print. That is, it was made from dust. Foil (silver) Side of Film (up) Electrodes Foil-backed Mylar Film Electrostatic Lifter Stun Gun Footprint in Dust Black Mylar Side on Dust Print: Foil Side Up. Electrode touching foil side + Ground Electrode Black Side of Mylar Film (down)

33. Arrows to Positive & Negative Electrodes Mylar Sheet Foil Side up The set up Fingerprint roller To Flatten Mylar Lifted Footwear Impression

34. Electrostatic Procedure • Place the metalized lifting film over the dust print. (dark side down) • Place the grounding plate about 8” next to the film. • Turn lifter so that the two metal probes on the back are resting on the grounding plate and the single probe is resting on the film. • Turn on the device and the film will be sucked down onto the print. • Gently brush over the film to remove any air bubbles. • Lift and you have your dust print.

35. Effects of Humidity and Temperature • The issue of humidity studied by investigators employing a similar technique ESDA for the detection of indented writing. • Studies show >>> humidity necessary … becomes detrimental when the relative humidity goes above 98% at room temperature … quality drops off. • At cold temperatures, even lower humidity causes a decrease in the quality of the highlighted indented printing. • ESDA is not an electrostatic lifter, but the principle is the same, and one might expect similar deterioration of the quality of prints using an electrostatic lifter. • Generally, normal use of electrostatic lifter under normal conditions of temperature and humidity should provide reliable results. • HOWEVER … absence of humidity … ESDA process requires humidity … opens the possibility that the absence or near absence of humidity may also affect the quality of electrostatic lifts.

36. Electrostatic detection apparatus (ESDA) • ESDA stands for Electrostatic Detection Apparatus. Used to produce a permanent 'lift' from paper which provides a visual map of indented impressions • Non-destructive. The paper under examination remains in exactly the same state, still available for other examinations. • Extremely sensitive - indentations found up to seven sheets below the page where the original writing was made. • ESDA works by stretching a Mylar film (like Clingfilm) over the document being examined. • Mylar film is electrostaticaly charged. • Where the paper is smooth, charging is generally uniform, however where the fibers of the paper have been disturbed by paper-paper contact caused by indentations, the electrostatic charge is different versus the background. • Creates latent image. In order to visualize this latent image, Black toner similar to that used in laser printers is applied to the surface of the Mylar. • Toner preferentially sticks where the electrostatic charge congregates • Areas of the indentations … an image with a grey toner background and darker toner traces in the areas where there are indented impressions. • Image is made permanent as a 'lift' by placing clear 'sticky backed plastic' over • Variables: Type of paper, the type of pen or stylus used, the number of sheets of paper between the writing and the sheet holding the impressions, the humidity at the time the impressions were made, the humidity at the time the ESDA lift was made, the method by which the toner is put onto the Mylar film*, and the amount and direction of the electrostatic charge put onto the Mylar film. • Not suitable for the examination of loose fibred paper such as newspaper or very glossy paper such as magazine covers. • Liquid will completely destroy the ESDA impression. … fingerprint treatment should be done AFTER any ESDA examination. • Toner can be put onto the Mylar film using three methods: cascading tiny glass beads coated with toner over the surface, puffing an aerosol of toner powder over the surface or using a device similar to a powder puff to apply the toner.

37. Storing Electrostatic lifts • Electrostatic lifts - fragile and must be protected. • Storing in flat boxes preserves better than other methods: • Do not roll in tubes. • A problem with flat storage is that dust is attracted to surface because the lift retains a residual static charge – it stops the dust from falling off the Mylar film. • Problem exacerbated when lifts exposed to open air or in low-grade cardboard. • Even lifts stored in a high quality cardboard will lose residual charge over time resulting in the complete loss of the impression. • Storage conditions: • High humidity increases rate of residual charge degradation • Store with a desiccant (silica gel) taped to inside of box. • Recommended to store the lifts so that the humidity does not exceed 50%.

38. If the print does not lift, it is a wet residue print. • Advantage of electrostatic lifting is preservation of the impression detail onto a black, Mylar surface. • What if, however, the impression does not lift? Is that proof that the impression was formed from a wet shoe? Differentiating Dry& Wet Residue 2D Impressions Impression at Scene Photograph Electrostatic Lift Successful Unsuccessful Dry Residue Impression Wet Residue Impression Photograph Enhance Preserve Impression Magnetic Powder Powder Suspension Chemical Enhancement Protect in Lift Box Protect with Gel Lifter Photograph

39. Gelatin Lifters (gellifters) For preservation purposes, they serve a similar function as electrostatic lifters • Effective multi-tasking tools. • Commercially available in two forms: • Rubber-backed gelatin-based in black, white or • Clear gelatin on a clear backing. • Semi-sticky surface lifts dry residue impressions AND wet residue impression. • Not reliable for differentiating between dry and wet residue impressions. • Do not require static charge. • “Sticky” surface “grabs” dust impression and sticks it to the surface of lifter. • Also pick up any surrounding, contaminating material such as dust, which can mask the lifted impression. Black Gellifter Lifting Footwear Impression

40. Gelatin Lifters (gellifters) • For dry residue prints, the light tan color of the impression is nicely off-set by the black of the gellifter. • Like electrostatic lifters, gellifters can lift impressions from hard surfaces, paper, carpeting, clothing, etc. • They are particularly useful on vertical surfaces. • Storage: • In uncovered high quality cardboard boxes works well. • Generally recommended that low grade cardboard boxes not be used because … tend to shed fibers onto the lifted image. • Also, breathable boxes will keep condensation from forming on the lifts. • Remove acetate sheet that comes with the lifter • Removing it later can remove some of the image. • Store the lifts in the same way as electrostatic lifts: high grade cardboard box without the acetate cover. • Over dusted or dense dust impressions can benefit from repeated removal of the acetate cover because this tends to remove some of the excess dust and render the lifted impression sharper.

41. Adapted from the BVDA gellifter brochure: http://www.bvda.com/EN/download/Gellifter_brochure.pdf,

42. Chemical Enhancements of 2D Impressions • Dry Residue Prints • Dust or Dirt? • 8-hydroxyquinoline • Fluorescent reaction with iron, aluminum and magnesium. • Spraying the reagent in the dark (outside this is difficult) gives yellow-white fluorescence that must be photographed immediately. • Testing the background before spraying the impression is critical • Testing a small part of the impression to see if the reagent is going to react with the dust/dirt present. 8-Hydroxyquinoline – UV Light

43. Chemical Enhancements of 2D Impressions Bromophenol Blue and Bromocresol Green Chemical Reagents Before Enhancement After Enhancement After Water Vapor Treatment Journal of Forensic Sciences, JFSCA, Vol. 41, No. 1, January 1996, pp. 23-26.

44. Oil or Fats • Iodine fuming • Iodine fuming followed by development with 7,8-benzophenone gives a blue/purple color. • First test a small part of impression and surface to see if the iodine is reacting. • Not a chemical reaction that takes place but more of an incorporation of the iodine into the matrix of the oil/fat. • Another way to visualize an iodine infused impression is to dust it with cornstarch and then hold a steam iron over the impression. The iodine will react with the starch to form a dark blue color. • Salt • In the winter, tires running over roads salted with NaCl (sodium chloride) will have the salt on the tread. • Transferred to a surface over which the vehicle travels. Spraying the impression with Silver Nitrate (AgNO3) will form silver chloride (AgCl) in those areas of the impression containing sodium chloride. • Shining a UV light or allowing sunlight to bake the impression will convert the AgCl to metallic Silver (Ago), which will appear dark gray or black.

45. Using Photography to Enhance • Photographic sequence important • Establishing ( • Midrange • Close-ups (examination quality or 1:1) • Record detail • With & without scale – In the same plane • Need to make 1:1 enlargements • Next to & parallel to print @ same level as impression • Made in plane of impression (vertical to impression) • Tripod is essential • Appropriate lighting • Oblique • ALS • RUVIS Camera Setup http://site.utah.gov/dps/impressions-fw-evidencecollection_000.htm

46. Photographing Footwear Impression Evidence • Examination quality photographs should always be taken of both two-dimensional and three-dimensional footwear impressions • Photographs are taken for later comparison with known footwear • A PROPER scale should ALWAYS be used when photographing footwear impressions • The scale should be on the same plane as the impression • Objects with impressions should be removed from the scene if possible, AFTER examination quality photograph taken • Always use a tri-pod • Fill the frame of photograph with your impression including your scale • Shade impression in sunny conditions • Use side lighting from different angles • take several shots

47. Proper Location of Light Source for 2-D Residue Prints Light Source Should Be 4-5 Feet From Impression From: Bodziak: Footwear Impression Evidence1

48. Existing Overhead Lighting Oblique Lighting 10 Degrees Oblique Lighting 25Degrees Oblique Lighting 45 Degrees Ambient Light + External Source From: Bodziak: Footwear Impression Evidence

49. Cross Polarization – Can Cut Glare High-Contrast B/W Photography • Film cameras • High-contrast B&W film • Kodak Tech Pan • Digital Cameras • Use B&W setting • Use software to convert color images • Filters • Subtract out the background • Gray impression on red floor • Use red filter on camera • Use UV or IR light • ALS • Polarizing filters can enable impressions to be photographed • One filter in front of oblique light source • Other filter in front of camera lens • Rotate filters to achieve max visibility of impression • Important technique for cutting glare

50. UV Light • UV wavelengths • UV spectrum : 10-400nm • Long-wave: 320-400 • Middle-range: 280-320 • Below 200: not useful • Use Reflected short-wave UV light - RUVIS • 18A filter over lens of camera • Filters out visible entering camera but not UV light Unaided Eye Long Wavelength UV Image http://www.ultravioletcameras.com/pdf/ETM-LongwaveUV.pdf (Photos Rachel Leintz)