Preserving the Crime Scene Chapter 3

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 2 Evidence and the Crime Scene A criminal investigation must be concerned with both people and things. Utilizing both human testimony and physical evidence, a prosecuting attorney can bring a case against a defendant.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 3 Evidence and the Crime Scene Evidence: Any item that helps to establish the facts of a related criminal case. It may be found at the scene of the crime or on the victim or taken from the suspect or the suspect’s environment.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 4 Evidence and the Crime Scene What exactly is forensic science? Forensic science – The application of science to law, and the use of science and technology to determine the value of evidence. Criminalist (or forensic specialist) – A person specifically trained to collect evidence and to make scientific tests and assessments of various types of physical evidence. In some jurisdictions investigators can call on these trained technicians to aid in the search for evidence, and they are often referred to as crime scene investigators (CSI).

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 5 Evidence and the Crime Scene Eight basic procedures during the crime scene investigation to gather and preserve evidence: Recognize or discover relevant physical evidence. Examine evidence to determine that it can be tested or compared in a crime laboratory. Collect evidence with care and diligence, according to standard procedures, and in a lawful manner. Carefully handle, package, and label evidence to avoid damage, loss, contamination, or questionable links in the chain of custody.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 6 Evidence and the Crime Scene Carefully record how, where, and by whom evidence was located to ensure that evidence has not been tampered with or altered. Carefully transport evidence to a laboratory, maintaining the proper chain of custody and security. Maintain the integrity of the chain of custody from the crime lab to the court after tests have been completed. Present or explain evidence in a court proceeding, substantiate the find if necessary, and document the chain of custody.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 7 Evidence and the Crime Scene The ultimate success or failure of a criminal investigation depends on: – Thoroughness exercised at the crime scene – Preserving – Collecting – Recording all available information

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 8 Pictorial Documentation of the Crime Scene Photographs of the scene of a serious criminal act should be taken as soon as possible after preliminary investigation priorities have been taken care of, before note taking, sketching, or the search of additional evidence begins.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 9 Photographing the Crime Scene The role of photographs in a criminal investigation is to present a logical story visually. Nothing in the crime scene should be disturbed before photographs are taken. When photographing a crime scene, follow the axiom “More is better.”

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 10 Camera Choices 35 mm Both black and white and colored film may be used at the crime scene. High-speed films are especially useful for capturing pictures even in low-light conditions. Traditionally, a single lens reflex (SLR) camera has been selected to photograph crime scenes. The SLR camera typically is compact and comes in a variety of formats, from manually focusing units to fully automatic units complete with automatic focusing, flash, and winding.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 11 Camera Choices Digital Digital cameras have a number of advantages when used in crime scene photography: – They require no chemical processing – Can be displayed on the camera immediately – Can be transferred to a computer and stored in an electronic database – Are now accepted in most courts

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 12 Camera Choices Megapixels Refers to picture image resolution. A mega equals 1 million. Pixels are the smallest unit of brightness and color. More pixels mean sharper, clearer, and better images. Video Good briefing tool for police officers who have not visited the crime scene. Can be an additional aid for the prosecutor in presenting a criminal case. They are not a substitute, however, for either photographs or sketches of the crime scene.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 13 Photo Organization Progress from the general to the specific. – long-range – mid-range – close-up Sometimes it may be necessary to include a measurement scale in photographs of objects at a crime scene. The first photograph on every roll of film shot at the crime scene should be a title card indicating: – Crime location – Date – Case identifier – Photographer – Roll number

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 14 Sketching the Crime Scene Sketches are useful in questioning witnesses and suspects and when writing investigative reports. Sketches offer accurate information about the placement of objects. Sketches show relationships and distances between things.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 15 Sketching the Crime Scene For a sketch or diagram to be legally admissible in court, it must meet the following requirements: – It must be part of a qualified person’s testimony. – It must recall the situation that the preparer saw. – It must express the place or scene correctly.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 16 Preparing the Sketch A crime scene sketch complements the notes and photographs taken during the crime scene investigation.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 17 Preparing the Sketch Try to use the largest scale possible. All sketches should include: – A compass or an orienting compass arrow indicating north. – A legend or key to explain letters, numbers, or symbols used. – An indication of the scale used.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 18 Sketching Methods Rectangular-coordinates method A sketching method that involves measuring the distance of an object from two fixed lines at right angles to each other. It is often used to locate an object in a room.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 19 Sketching Methods Triangulation method A sketching method that requires measuring the distance of an object along a straight line from two widely separated, fixed reference points.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 20 Sketching Methods Baseline method – A sketching method that takes measurements along and from a single reference line, called a baseline, which can be established by using a length of string, a chalk line, or some convenient means.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 21 Sketching Methods Compass point method – A sketching method that requires a protractor or some method of measuring angles between two lines. – One point is selected as the origin and a line extended.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 22 Sketching Methods Cross projection method – A sketching method in which the ceiling appears to open up like the lid of a hinged box, with the four walls opening outward – Measurements are then indicated from a point on the floor to the wall.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 23 Equipment for Sketches A supply of pencils (medium or hard lead) Graph paper and blank paper A clipboard or other solid portable drawing surface A metal tape measure of at least 50 feet A folding ruler, such as the standard 6-foot folding ruler used by carpenters, for short measurements A 12- or 15-inch ruler for drawing straight lines, drawing to scale, or making very short measurements A reliable compass or some other means of finding north A protractor for drawing and measuring angles

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 24 Equipment for Searches Latex gloves Compass Camera, film String Rope Knife Evidence tags Steel tape measure Assorted containers Ruler Assorted envelopes Pens Pill boxes Indelible marker Magnifier Paper Test tubes Fingerprint kit Plastic bags Shovel Bottles Flashlight, batteries Cellophane tape Probing rod Ax Wire Saw First-aid kit Wrecking bar Metal detector Chalk, chalk line

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 25 Discovering and Recognizing Evidence After the crime scene has been photographed and sketched, you can begin a search.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 26 Search Patterns Spiral search pattern – A search pattern typically used in outdoor areas and normally launched by a single person. – He or she begins at the outermost corner and walks in a decreasing spiral toward a central point.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 27 Search Patterns Strip search pattern – A search pattern in which the space to be searched is divided into a series of lanes – One or more searchers proceed up and down the lane, continuing until the area has been completely searched.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 28 Search Patterns Grid search pattern – A search pattern that consists of two strip searches, the second perpendicular to the first – It allows the area to be viewed from two angles.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 29 Search Patterns Zone search pattern – A search pattern in which the area is divided into four quadrants, each of which is then examined with one of the other patterns.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 30 Search Patterns Pie (or wheel) search pattern – A search pattern in which the area is divided into pie-shaped sections, usually six in number. – Each section is then searched, usually by a variation of the strip search.

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 31 Collecting and Marking Evidence The court will want answers to the following questions about evidence collected at the crime scene: – Who found it? – What did it look like? – When was it found? – Where was it found, and what is its relation to other objects at the scene? – Where was it held from its collection to its presentation in court?

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 32 Collecting and Marking Evidence The investigator who finds the evidence should place his or her personal identifying mark on it. – The mark should be permanent and capable of positive identification. Evidence that cannot be physically marked--such as bird shot or liquids--should be placed in an appropriate container. – This receptacle should then be sealed and identified with a label or property tag indicating: the title of the case the officer’s name or initials the date the time the specific location where it was found

Copyright ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 33 Collecting and Marking Evidence A fairly common evidence container in use today is a 9 by 12-inch manila envelope. Standard of comparison – A model, measure, or object with which evidence is compared to determine whether both came from the same source.