Laboratory Activity Report—Impression Evidence: Shoes, Tires, Tools
Forensics Student Manual 3 Copyright Information Forensics Lab Manual © 2015 eScience Labs, LLC. All rights reserved. This material may not be repro-duced, displayed, modified, or distributed, in whole or in part, without the express pri-or written permission of eScience Labs. Appropriate citations must accompany all ex-cerpts and/or quotations. For written permissions, please contact [email protected] Note: Educational institutions and customers who have purchased a complete lab kit may reproduce the manual as a print copy for academic use provided that all copies include the following statement: “© 2015 eScience Labs, LLC. All rights reserved”. This manual was typeset in 11 Arial and 12 Chalet-London 1960. Arial font provided by Microsoft Office Suite, 2010. Chalet-London 1960 font licensed from House Indus-tries, 2011. The experiments included within this lab manual are suitable for supervised or unsu-pervised learning environments. eScience Labs assumes full liability for the safety and techniques employed within this manual provided that all users adhere to the safety guidelines outlined in the mandatory eScience Labs Safety Video, Preface, and Appendix. All users must understand and agree to the eScience Labs safety guide-lines prior to beginning their lab experiments. eScience Labs does not condone use of the lab materials provided in its lab kits for any use outside of the curriculum express-ly outlined within the lab manual. 5 Acknowledgements Acknowledgements The Forensics Lab Manual is a collaborative development which we are delighted to provide to higher education curriculum. Key contributors, including Cindy Higgins (M.S., Educational Instructional Design and Technology) and Dr. Max Houck (Ph.D., Forensic Chemistry), have brought creativity, rigor, intelligence, and industry applica-bility to this lab kit. We have greatly enjoyed working with this team, and look forward to serving students around the world with our hands-on lab experiments. 7
Table of Contents
Forensics Lab Manual
Table of Contents Impression
Evidence: Shoes, Tires, Tools 9 Using Your Lab Kit Using Your Forensics Lab Kit To successfully use and get the most learning and enjoyment out of your Forensics lab kit here are some tips before you begin: Refer to your course’s syllabus for the due date and sequence of your lab as-signments. Your instructor may not assign all of the labs or may not assign them in the order they are presented in the lab manual, on the Student Portal, or your school’s Learning Management System (LMS). As soon as you receive your kit, compare the contents of your kit to the inven-tory insert that comes in your kit. If you are missing any items or any item was broken during delivery call eScience Labs at 1-888-375-5487 or email [email protected] immediately for a replacement. There are a few materials that you will need to complete your experiments that are not provided in your kits such as fresh produce or water. Review the Time and Materials section (after these tips) for a list of these items. The Time and Materials section also includes an estimate of the amount of time it will take a student to complete each lab to help you plan to set aside time to complete them. Some experiments may require a few days to a week for observation, so don’t wait until the last minute to begin experiments. Before performing an experiment, read through the procedure thoroughly so that you know what to expect when you begin to handle materials. Most importantly, have fun! 11 Time and Materials Time and Materials Required There may be a few additional materials required to complete your lab experiments which are not included in your eScience Labs kit. Please review the procedures and plan accordingly. Note that the times listed are approximations and may differ de-pending on the assignments required by your instructor and/or your previous subject knowledge. Evidence and Crime Scenes Time Required: 1 hour Additional Materials: Camera (camera phones are acceptable), Scissors, Blue or Black Ink Pen, Computer, Internet Access Fingerprinting Time Required: 1.5 hours Additional Materials: Camera (camera phones are acceptable), Right Hand Fingerprints, Left Hand Fingerprints, Paper Towel or Clean Towel, Soap and Water (for hand washing), Work Surface (See Step 1 in Experi-ment 1 Procedure), Glass Surface (window, bottle, etc.), Metal surface (chair, door knob, etc.), Skin Oil (from face) Blood Time Required: 1.5 hours Additional Materials: Camera (a camera phone is acceptable), Paper Tow-els, Pencil, Adjacent Floor and Wall, Flat Surface If you are allergic to nitrile, please contact eScience Labs at [email protected] and we will send you an alternative type of safety gloves. Some of your kit materials, such as rubber bands, may include latex. Always wear your nitrile safety gloves when working with these items! 12 Time and Materials Impression Evidence: Shoes, Tires, Tools Time Required: 1 hour Additional Materials: Camera (a camera phone is acceptable) 13 Safety Information Lab Safety Always follow the procedure in your laboratory manual and these general rules: Lab Preparation Please thoroughly read the experiment procedure before starting. If you have any doubt as to what you are supposed to be doing and how to do it safely, please STOP and then: Double-check the manual instructions. Check www.esciencelabs.com for updates and tips. Contact us for technical support by phone at 1-888-ESL-Kits (1-888-375-5487) or by email at [email protected]. Read and understand all labels on chemicals. If you have any questions or concerns, refer to the Material Safely Data Sheets (MSDS) available at www.esciencelabs.com. The MSDS lists the dangers, storage requirements, exposure treatment and disposal instructions for each chemical. Consult your physician if you are pregnant, allergic to chemicals, or have other medi-cal conditions that may require additional protective measures. Proper Lab Attire Remove all loose clothing (jackets, sweatshirts, etc.) and always wear closed-toe shoes. Long hair should be pulled back and secured. All jewelry (rings, watches, necklaces, earrings, bracelets, etc.) should be removed. Safety glasses should be worn at all times. In addition, wearing soft contact lenses while conducting experiments is discouraged, as they can absorb potentially harmful chemicals. When handling chemicals, always wear the protective glasses, gloves, and apron pro-vided in your safety kit. 14 Safety Information Performing Experiments Do not eat, drink, chew gum, apply cosmetics, or smoke while conducting an experi-ment. Work in a well ventilated area and monitor experiments at all times, unless instructed otherwise. When working with chemicals: Never return unused chemicals to their original container to avoid contamination. Never place chemicals in an unmarked container to avoid identification or proper disposal problems. Always put lids back onto chemicals immediately after use to avoid contamination or potential hydration problems. Never ingest chemicals. If this occurs, seek immediate help. Call 911 or “Poison Control” 1-800-222-1222 Never leave a heat source unattended. If there is a fire, evacuate the room immediately and dial 911. Lab Cleanup and Disposal If a spill occurs, consult the MSDS to determine how to clean it up. Never pick up broken glassware with your hands. Use a broom and a dustpan and discard in a safe area. Do not use any part of the lab kit as a container for food. Safely dispose of chemicals. If there are any special requirements for disposal, it will be noted in the lab manual. When finished, wash hands and lab equipment thoroughly with soap and water. Above all, use common sense. Read the manual carefully and pay close atten-tion to the safety concerns prior to starting an experiment. 15 Student Portal Student Portal Resources You can find supplemental resources including, videos, simulations, and tutorials on the eScience Labs Stu-dent Portal. The following list outlines available resources by lab: Evidence and Crime Scenes Evidence and Crime Scenes Concept Animation Evidence and Crime Scenes Lab Drill Virtual Microscope Fingerprinting Fingerprinting Concept Animation Fingerprinting Lab Drill Blood Blood Concept Animation Blood Lab Drill Impression Evidence: Shoes, Tires, Tools Impression Evidence: Shoes, Tires, Tools Concept Animation Impression Evidence: Shoes, Tires, Tools Lab Drill Access your Student Resources with these easy steps: If you purchased a kit directly from www.eScienceLabs.com, your user account already has access to the Student Resources for your course. To access these, please visit www.eScienceLabs.com, and click on the Stu-dent tab. Then, enter your username and password. On the following page, scroll down until you see the name of your lab kit or prod-uct SKU. This should be a hyperlink. Click this hyperlink. You will see a series of topics, each of which contain lab information or virtual as-sets. If you purchased a kit from somewhere else (e.g., your bookstore), you’ll need to set up a new user account. Begin by going to www.eScienceLabs.com, and clicking the Cre-ate Account button in the upper right-hand corner. After you are registered and logged in, click the HAVE A CODE button, located on the right side of the home page. Enter the access code located on the underside of your lab kit box lid and press Submit. Click on the Student tab from the home page. On the following page, scroll down until you see the name of your lab kit or product SKU. This should be a hyperlink. Click this hyperlink. You will see a series of topics, each of which contain lab in-formation or virtual assets. Lab Impression Evidence: Shoes, Tires, Tools 66 Impression Evidence: Shoes, Tires, Tools Learning Objectives Explain the role of shoe, tire, and tool mark analysis in forensics Perform a tire track analysis Introduction Impression evidence is c r eat ed w h en tw o o bjec t s c o m e i n c o nt ac t with each other and leave characteristics on the surface of one or both of the objects. Impressions can be two dimensional (2D) or three dimen-sional (3D). 2D impressions have length and width, but no depth, such as shoeprints on a tile floor. 3D impressions have depth, in addition to length and width, such as the dent a tool leaves after striking a surface. Sometimes, impression evidence contains pattern evidence, class char-acteristics common to a group of objects, such as a shoe tread associat-ed with shoes produced by a certain company. When possible, the sur-face containing the impression evidence should be collected and trans-ported to a laboratory for analysis. If the impression cannot be collected, a CSI can lift a 2D impression or make a mold of a 3D impression. Lifting an impression involves transferring it from one surface to another with an adhesive material, such as tape. Making a mold of an impression in-volves applying a material to the impression that fills in all of the details of the impression and hardens to preserve its 3D shape. Photographing Impression Evidence Before a mold or lift of impression evidence is created, a crime scene photographer documents the impression via photograph to record the impression in its original state and position at the scene (Figure 1). Photographing impression evidence, such as shoeprints, is done with the camera lens positioned parallel or 90 degrees to the impression. A photomac-rographic scale is also included next to the impression so that the true size can be gauged and a scale can be produced. If the camera is not oriented exactly 90 degrees above the impression, the actual size of the impression can’t be determined, leading to misinterpretation of evidence. To help maintain a 90 degree angle with the impression, photomacrographic scales include circles. Photographing the impression with lighting at various angles helps to capture its details. Figure 1: Photograph of a foot-print with a photomacrographic scale. 67 Impression Evidence: Shoes, Tires, Tools Tire Treads and Tracks The surface design of a tire that increases friction and minimiz-es slippage is referred to as the tread. Tire treads are pro-duced in many intricate designs that can be traced to a specific tire manufacturer. In addition, vehicle tires accumulate materi-al, such as gravel and dirt, in the tread, sustain damage, such as cuts, and undergo normal wear. All these characteristics are useful in tire examination (Figure 2). Tire tracks show the rela-tionship between two or more tires (Figure 3). When possible, tire impressions from each tire should be col-lected. Tire impression evidence analysis may reveal: The approximate dimensions of a suspect vehicle (wheel base measurement and turning diameter) Sequence of events in regards to vehicle movement Tire tread characteristics (noise reduction feature, design, and unique wear patterns) Figure 2: Tire tread. True or False? A tire tread can indicate the relationship between two or more tires. Knowledge Check! Figure 3: Tire tracks. 68 Impression Evidence: Shoes, Tires, Tools Tool Marks Another type of impression evidence that may be found at a crime scene is a tool mark, impressions that are the result of two objects brought into contact with each other. Tool marks are commonly found on doors, windows, or other openings where forcible entry has been attempted. Some-times, tool marks may even be present on skeletal remains if stabbing or dismemberment occurred. The tool and tool mark will be photographed with a scale and examined for any trace evidence (Figure 4). MikrosilTM, a material useful in microscopic observations, is often used for making casts of fine details. Figure 4: Screwdriver documented with a scale. 69 Impression Evidence: Shoes, Tires, Tools Experiment 1: Tire Track Analysis In this experiment, you will analyze tire track patterns. Procedure 1. Use the permanent marker to label the bottom of a sheet of construction paper “Linear Path.” 2. Remove the lid of the fingerprint ink pad and apply ink to the entire surface of all four tires of the toy car by rolling each tire across the ink pad. 3. Place a ruler parallel to the long edges of the construction paper. This will help the toy car maintain a line-ar path. 4. Place the toy car just above the label on the construction paper facing away from you. Keeping your hand on the car, roll it in a linear path alongside the ruler until the front tires reach the end of the paper (Figure 5). Leave the car where it rests when you stop rolling it. 5. Use the permanent marker and the position of the car to label which tire created each track. 6. Use a camera to photograph the tire tracks. Note: You will need to download, scan, or print the photographs to be included with your lab report. 7. Use the permanent marker to label the bottom of a second sheet of con-struction paper “Curved Path Right to Left.” 8. Use the fingerprint ink pad to apply ink to the entire surface of all four tires of the toy car. Materials Fingerprint Ink Pad Toy Car Permanent Marker Ruler 3 White Construction Paper Sheets *Camera (a camera phone is acceptable) *You Must Provide Figure 5: Step 4 reference. The blue rectangle represents the car and the arrow indicates the direction to roll the car. 70 Impression Evidence: Shoes, Tires, Tools 9. Place the car on the bottom right hand corner of the construction paper and roll the car in a curved path from the bottom right corner to the top left corner of the paper until the front tires reach the edge of the paper (Figure 6). Leave the car where it rests when you stop rolling it. Note: You may need to hold the paper flat with one hand while roll-ing the car with the other. You may need to use less pressure when rolling the car on a curved path than when you rolled the linear path. 10. Use the permanent marker and the position of the car to label which tire created each track. 11. Use a camera to photograph the tire tracks. Note: You will need to download, scan, or print the photographs to be included with your lab report. 12. Repeat Steps 7 – 11 with a new sheet of paper. Label the paper “Curved Path Left to Right”, and roll the car on a curved path from the bottom left corner to the top right corner of the paper. Figure 6: Step 9 reference. The blue rectangle represents the car and the arrow indicates the direction to roll the car. . Appendix Good Lab Techniques 73 Good Lab Techniques Good Laboratory Techniques Science labs, whether at universities or in your home, are places of adventure and discovery. One of the first things scientists learn is how exciting experi-ments can be. However, they must also realize science can be dangerous without some instruction on good laboratory practices. Read the protocol thoroughly before starting any new experiment. You should be familiar with the action required every step of the way. Keep all work spaces free from clutter and dirty dishes. Read the labels on all chemicals, and note the chemical safety rat-ing on each container. Read all Material Safety Data Sheets (provided on www.eScienceLabs.com). Thoroughly rinse labware (test tubes, beakers, etc.) between experi-ments. To do so, wash with a soap and hot water solution using a bottle brush to scrub. Rinse completely at least four times. Let air dry Use a new pipet for each chemical dispensed. Wipe up any chemical spills immediately. Check MSDSs for special handling instructions (provided on www.eScienceLabs.com). Use test tube caps or stoppers to cover test tubes when shaking or mixing – not your finger! Figure 1: A bench coat or underpad helps prevent any spilled liquids from contami-nating your work surface. A B C Figure 2: Special measuring tools in make experimentation easier and more accu-rate in the lab. A shows a beaker, B graduated cylinders, and C test tubes in a test tube rack. 74 Good Lab Techniques When preparing a solution, refer to a protocol for any specific instructions on preparation. Weigh out the desired amount of chemicals, and transfer to a beaker or graduated cylinder. Add LESS than the required amount of water. Swirl or stir to dissolve the chemical (you can also pour the solution back and forth between two test tubes), and once dissolved, trans-fer to a graduated cylinder and add the required amount of liquid to achieve the final volume. A molar solution is one in which one liter (1L) of solution con-tains the number of grams equal to its molecular weight. For example: 1M = 110 g CaCl x 110 g CaCl/mol CaCl (The formula weight of CaCl is 110 g/mol) A percent solution can be prepared by percentage of weight of chemical to 100ml of solvent (w/v) , or volume of chemical in 100ml of solvent (v/v). For example: 20 g NaCl + 80 mL H2O = 20% w/v NaCl solution Concentrated solutions, such as 10X, or ten times the normal strength, are diluted such that the final concentration of the solution is 1X. For example: To make a 100 mL solution of 1X TBE from a 10X solution: 10 mL 10X TBE + 90 mL water = 100 mL 1X TBE Always read the MSDS before disposing of a chemical to insure it does not require extra measures. (provided on www.eScienceLabs.com) Avoid prolonged exposure of chemicals to direct sunlight and extreme temperatures. Immediately se-cure the lid of a chemical after use. Prepare a dilution using the following equation: Where c1 is the concentration of the original solution, v1 is the volume of the original solution, and c2 and v2 are the corresponding concentration and volume of the final solution. Since you know c1, c2, and v2, you solve for v1 to figure out how much of the original solution is needed to make a cer-tain volume of a diluted concentration. Figure 3: Disposable pipettes aid in ac-curate measuring of small volumes of liquids. It is important to use a new pi-pette for each chemical to avoid con-tamination. 75 Good Lab Techniques If you are ever required to smell a chemical, always waft a gas toward you, as shown in the figure below.. This means to wave your hand over the chemical towards you. Never directly smell a chemical. Never smell a gas that is toxic or otherwise dangerous. Use only the chemicals needed for the activity. Keep lids closed when a chemical is not being used. When diluting an acid, always slowly pour the acid into the water. Never pour water into an acid, as this could cause both splashing and/or an explosion. Never return excess chemical back to the original bottle. This can contaminate the chemical sup-ply. Be careful not to interchange lids between different chemical bottles. When pouring a chemical, always hold the lid of the chemical bottle between your fingers. Never lay the lid down on a surface. This can contaminate the chemical supply. When using knives or blades, always cut away from yourself. Wash your hands after each experiment. 77 Credits Credit Saferstein, R., (2013). Forensic science from the crime scene to the crime lab. (2nd ed.). San Fran-cisco, California: Pearson Education Inc. Technical Working Group on Biological Evidence Preservation. The Biological Evidence Preserva-tion Handbook: Best Practices for Evidence Handlers. U.S. Department of Commerce, National Insti-tute of Standards and Technology. 2013. www.canstockphoto.com © 2016 eScience Labs, LLC All rights reserved
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