Trace evidence can be found at a crime scene in a number of different forms, including hairs and fibers, glass, or soil. High-velocity impact fractures �mG�6�]k�3�c�B�����z�d�B.QO�g,uB �4��(�C.�`#*�=�@�R���٤G�G&U8N�X�P�!����U��ꬵna�㤃�� ^�^ƟV�"�~_彆'(! Title: Microsoft PowerPoint - Glass and soil.ppt Created Date: 16:41 3/20/2007 The method used to establish this is the 4R Rule: Ridge lines on Radial fractures are at Right angles to the Rear. True False: A forensic geologist is often called upon to individualize soil to a particular location. Terms. This layering effect gives a sample greater variation, and thus. Standard/reference soil samples should be collected at the site of the crime, at various, intervals within a 100-yard radius of the crime scene, and at all possible alibi locations that the. No regular pattern of radial or concentric lines, Show little if any curve patterns along the edges, Expansion of glass occurs first on the side exposed to the heat, Look for glass on the suspect & victim as well as the crime scene, Mark with a diamond point or Carborundum pencil, adhesive tape or grease pencil may also work, Mark only where there is no trace evidence, such as fingerprints or blood, Fragments too small for markings go into containers, Wrap glass & fragments in soft paper to avoid further breakage or damage to trace evidence, Package glass samples in solid containers to avoid further breakage, Package suspect’s shoes/clothing in paper. Why is soil collected from suspect automobiles left in lump form? Terms. Concentric fractures connect the radial fractures in a pattern similar to a spider web. W ##~�fG�'T�4ٙ�s95�:����X,k! Glass analysis includes determining the type of glass based on glass fragments. For a concentric fracture, the perpendicular end always faces the surface on which the force originated. A mineral is a naturally occurring crystalline solid that can be identified by its physical properties. can’t bend or bulge appreciably Glass broken by heat or explosion. For a limited time, find answers and explanations to over 1.2 million textbook exercises for FREE! �ʩ8�lt�y7]S�[�c�ğ�N True False: A forensic geologist is often called upon to individualize soil to a particular location. If concentric and radial cracks are on one side only this is the side of impact. Module 4_ Page 9_ Paint _ Polarized Light Microscopy (PLM)_ PHA6850-Principles of Forensic Science.p, Module 4_ Page 18_ Individualization of Hair_ PHA6850-Principles of Forensic Science.pdf, Module 4_ Page 5_ Light Microscopy Continued_ PHA6850-Principles of Forensic Science.pdf, Module 4_ Page 13_ Identifying Glass Particles_ PHA6850-Principles of Forensic Science.pdf, Module 4_ Page 11_ Paint _ SEM-EDS, XRF, XRD_ PHA6850-Principles of Forensic Science.pdf, Module 4_ Page 6_ Polarized Light Microscopy_ PHA6850-Principles of Forensic Science.pdf, Module 4_ Page 4_ Light Microscopy_ PHA6850-Principles of Forensic Science.pdf, 2019_Book_ImageAnalysisAndProcessingICIA_part2.pdf, Copyright © 2020. A high-speed projectile striking a piece of glass will produce a cone or crater. Glass does not break into regular pieces with straight line fractures. 2002). If fired from an angle, entry hole will be oval. Performance & security by Cloudflare, Please complete the security check to access. Contaminants or residues from the inside surface will feel different than the outside surface and are helpful in determining the sides. How can soil evidence be valuable even if the site of the crime has not been ascertained? 1 0 obj However, the entire fractured pane or window can be helpful when determining direction and sequence of force. ?�7�廢^�|��O�Qk�[_&�����'��Io�;`��w�'Xb"�n��w�%��CY�DIm���`�Hd4~0q&���Q�*�O(��������AN,Z��;v�?i�I$���Qjd�v�vzbq�f����Df�c�*.~���;#���J{Y�K~�nj Fracture and stress lines can be used to guide a mechanical fit between two pieces of glass. stream The 4R rule is unreliable for laminated glass, tempered glass, and small windows tightly held in a frame (Koons et al. makes it easier to compare the sample to soil samples found at the site of an accident. Unfortunately, the absence of radial or concentric fracture lines prevents … Once the technician finds radial fracture and determines which side of the glass faced where, they must look at the broken edge of the glass. The 3R rule helps in remembering this effect: Radial cracks form a Right angle on the, Module 4: Page 14: Glass Fracture Matching: PHA6850-Principles of Forensic Science. 7.2.2. What is the 3R rule and how is it applied to the analysis of glass fractures? Broken or discarded plastic items can be melted and remoulded to form other useful substances. Glass Safety Legislation – the law and glazing. The first shot’s radial fractures will extend completely while the subsequent shots’ radial fractures will be stopped or cut off as they come into contact with prior fractures. For other wavelengths and for pulsed lasers, other limits apply. This rule. Radial fractures are similar to the spokes of a wheel. A gas has. The 4R rule is unreliable for laminated glass, tempered glass, and small windows tightly held in a frame (Koons et al. RI is the manner in which light passes through the glass. Windshield glass is safety glass; cracking is often incomplete. <> Enable and reload. This preview shows page 1 - 2 out of 2 pages. Cloudflare Ray ID: 5ec961267b2c2af4 Glass initially bends away when a force is applied. This document provides information on the analysis of glass evidence. Pattern can be used to determine the direction and amount of force. <> Basic properties, such as color, thickness, and curvature, can also help to identify different samples of glass just by looking at them. endobj no “point of impact” curved, smooth edges at break points. Define the terms element and compound and name the smallest unit of each. At what locations should soil standard/reference samples be collected? samples to determine whether they have the same origin. Concentric cracks come later (“secondary”) and are on the same side as the force. When performing a mechanical fit, the ridges from two matching fragments will mesh together. By analyzing the radial and concentric fracture patterns in glass, the forensic scientists can determine the detection of impact A high velocity projectile such as a bullet often leaves a hole that is wider of the exit side, and hence its examination is important in determining the direction of impact. 3 0 obj Bits of the glass can fly backward (backscatter), possibly creating trace evidence. The first step in this method is to find radial fractures that are within the first concentric fracture. 3R rule: Radial cracks give rib marks that make; Right angles on the ; Reverse side from where the force was applied; Exceptions to the Three R Rule. Photographs of fracture ridges and lines can be used. endobj The first step in this method is to find radial fractures that are within the first concentric fracture. Concentric fractures connect the radial fractures in a pattern similar to a spider web. Subsequent ones will have fractures that stop @ original fractures. Your legal responsibilities with regard to glazing are governed by two key areas; This phenomenon is referred to as the 4R rule, (Ridges on Radial cracks are at Right angle to the Rear.) Impacting force is dispersed over a larger area. What is the most important consideration when collecting soil samples from a crime scene? Glass Fractures (6 of 8) 3R rule: Radial cracks give rib marks that make Right angles on the Reverse side from where the force was applied Glass Fractures ... – A free PowerPoint PPT presentation (displayed as a Flash slide show) on PowerShow.com - id: 3bda7a-NTYzY
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