![]() (ii) Clean the bottom of the shoe from any dust. Collect the footprint left on the A4 paper. ![]() The size and shape of the shoe may be misinterpreted Worksheet 3.3 Analysis of footwear impression Apparatus: 1 sample shoe, 1 A4 carbon paper, 1 paper clay, 3 A4 paper Experiment (i) Put on the sample shoe, then step on a carbon paper with an A4 paper underneath (both pieces of paper are put on the floor). Case 1 is a wrong method since any angle other than 90o in taking the photo will cause distortion of the image. Suggested ans : The ratio in case 2 is very close to that of the real shoe while a significant discrepancy appears for case 1. Comment on the accuracy of the methods in recording trace evidence in the crime scene. Case 1 a Ratio : b Case 2 = Real shoe = Compare the ratio of case 1 and case 2 with the ratio of the real shoe making the footprint. Measure the width and length of the footprints and calculate their ratios. On inclined plane Correct Incorrect Case 1 Case 2 a1 a2 3 Actual sizes of images and b2 b1 real shoe are not important as the ratios of dimensions are used to indicate whether there is any distortion on the images. Demonstration 2 Taking photo of a footwear impression The same footprint placing on the floor is to be shot by camera at TWO different angles (case 1 and case 2), the photos taken will be projected on the screen. Analysis of a footwear impression may include comparing a suspect’s shoe to either photographs or castings made of dental stone (similar to plaster of paris). Oblique light is used because it can cause large degree of diffuse reflection, reflection Diffuse reflection the light raysRegular reflect from the footprint diverge in different directions and make it more visible. When parallel light rays enter rough surface, they will reflect at different direction. Glass) the rays will reflect at the same direction with each other. 2 Want to know more ? When parallel light rays enter flat and smooth surface (eg. camera DARK BACKGROUND observer Due to the little bit torch roughness caused by the footprint, light will reflect at different direction and the 3D impression of the Footprint footprint can be observed. discovery of footprint by oblique light Demonstration 1 Title : Use of oblique light source to observe and record latent footprint. Use light colour footprint on dark surface for better result. They may also be collected using an electrostatic dust lifting process. ![]() Since many footprints are latent, the impressions may be dusted with fingerprint powder to be photographed or lifted with tape. hiking shoes) 3 Depth of footprint on soft material 4 wear patterns and specific damages 5 trace materials, such as soil, Weight of suspect Walking habit of suspect Places where suspect had visited tar, rocks, and paint Worksheet 3.2 Photographing footprints Taking photographs for footprint are very common in a crime scene. significance Real size of suspect’s foot approximate height of suspect Sex of the suspect Suspect’s hobbies 1 (e.g. Sample footprint Discuss with your group members “What are the important features in footprints and their significance (refer to the given example)?: e important features Size of footprint 1 Shape of footprint 2 Type and brand. This evidence can provide investigators with certain information that can assist them in locating a suspect. Lesson 3 Footwear Evidence Worksheet 3.1 – Introduction of footwear evidence Footwear impressions are often discovered at the scene of the crime.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |