CHEM 4930 Forensic Science Analysis. Lecture 4

Transcription

1 CHEM 4930 Forensic Science Analysis Lecture 4

2 Documentation Documentation The most important activity that is performed at a crime scene Types of documentation Notes Photographs Sketches

3 Taking Photographs Photography of the crime scene should begin as soon as possible. The well-worn saying a picture is worth a thousand words certainly holds true with crime scene photography. Before a detailed examination of the crime scene is made or before any items are even touched or moved, the crime scene should be photographed. Photographs should be taken to clearly and accurately depict the scene as it was found, the paths taken by the criminal to the scene, the point of entry, the exit and escape routes.

4 Taking Photographs How many photographs should be taken? No simple answer, but as a general rule, it is better to overshoot a crime scene (take more photographs than are necessary) than to economize and take too few. Photographs serve a number of purposes: They aid in refreshing the memories of witnesses and investigators Show relationships of items of evidence at the crime scene. They help to convey an image of the crime scene and circumstances of the crime to the jury.

5 Taking Photographs Three types of crime scene photographs: Overall Mid-range (evidence establishing) Close-up

6 Taking Photographs Overall photographs The purpose of overall photographs is to depict the general condition and layout of the scene. Taken from a natural perspective, which is the viewpoint of the scene that has the photographer standing at full height. Want to capture how the scene is oriented, where major visible landmarks are (door, furniture, bodies), and the condition of the scene prior to significant alteration. Overall photographs are the first photographs taken Overall photographs put you at a location

7 Taking Photographs Overall photographs exterior Relate the crime scene to the general surrounding area. If the crime was committed indoors, overall photographs also show external views of the building in which the crime occurred. It is the job of the crime scene investigator to walk the viewer of the photographs into the crime scene from its outer perimeter.

8 Taking Photographs When possible, the crime scene photographer should begin at the intersection closest to the crime scene. When photographing street signs, do so in a way that indicates to the viewer which of the two street names is the one on which the crime occurred. When composing this shot, make the street the crime occurred on more predominant in the photograph. Both street names are visible, but the street in which the crime occurred on is more prominent.

9 Taking Photographs Exterior Overall photographs Once at the crime scene building, the entire exterior should be photographed The purpose is to show all the possible ways the suspects could have entered or left the building. Even when that information is already known, further information could be developed later. When taking exterior overalls, include a photograph of the building of the address or the building name. If it is possible to photographs the exterior of the building with the film plane parallel to the walls of the building, this is preferred, Rather than diagonal viewpoints.

10 Taking Photographs

11 Taking Photographs Interior overall photographs Taking interior overall photographs is usually a priority because the scene will have to be documented as found before anything can be moved. Depending on the nature of the crime being investigated, many rooms may need to be photographically documented, or just one room may need to be photographed. Understand the importance of photographing both involved and noninvolved rooms. Interior overall photographs are the bridge between exterior overall and the individual items of evidence within the crime scene. After the exterior is photographed and before the evidence is photographed, the interior is photographed.

12 Taking Photographs Interior overall photographs Once inside the crime scene room, take a complete set of interior overall photographs. The phrase interior overall photographs suggests that a full 360 degree view of the room will be photographed, which is true, but somewhere along the line, the purpose of interior overall photographs seems to have gotten lost. Usually the room is photographed from each of the four corners while facing the opposite corner, and if the room was big enough so that these four shots with a 50mm lens did not encompass the entire room, it was suggested to use a wide-angle lens. Problem? Are these a fair and accurate representation of the scene? Makes it look like the room is bigger than it really is.

13 Taking Photographs Interior overall photographs Another purpose of interior overall photographs is that all the evidence within the crime scene will need to be related to the fixed features of the scene. When we take interior overall photographs, we are documenting those fixed features. Most interior photographs are taken from eye level or a natural perspective.

14 Taking Photographs

15 Taking Photographs Overall photographs are taken in two distinct iterations during crime scene processing. The first occurs prior to the introduction of any scales, photo placards, or the like. This initial set of photographs is used effectively for eliminating any issue regarding alteration of the original condition of the scene. The second occurs as specific areas and items of evidence in which photo placards (numbers or letters) are introduced. In scenes involving multiple rooms or widely dispersed areas, additional overall photographs may be necessary to properly orient the viewer as to how one room relates to another.

16 Taking Photographs Evidence establishing or mid-range photographs Serve an important purpose or role in terms of evidence in the scene which may very small and which would not even appear as recognizable objects in the overall photographs. The other purpose evidence establishing photographs serve is to the frame the item in conjunction with some obvious landmark evident in the overall photographs.

17 Taking Photographs Close-up photographs To compose a close-up photograph properly, frequently the photographer must abandon the natural perspective point of view. Many times, the photographer will be bent over or leaning over the evidence, if not actually kneeling, to get close enough to fill the frame with the evidence. Different types of close-up photographs: 1. As found, As is, In situ The first close-up photograph should show the evidence as found in the scene before any alteration or movement of anything in the scene. Nothing should be added to the scene, and nothing should be taken away from the scene when the evidence is first photographed. = in situ in the situation it was originally found before any movement.

18 Taking Photographs Regardless of the size of the evidence, there should be an attempt to fill the frame with the evidence. Can usually be done with a normal lens if the item of evidence is textbook sized or larger If it is smaller than a textbook, magnification will be required. If the evidence is important enough to photograph, why not make it as large as possible, so small aspects of the evidence may better be seen.

19 Taking Photographs Many photographs of items of evidence, usually with a scale, will eventually be used in court. Having an as is photograph will resolve any issues about the convenience of having the scale laid alongside the evidence and the hiding or covering of some other evidence. With a fully labeled scale, on the same plane. A second close-up photograph that should be taken of every item of evidence is one that includes a fully labeled scale alongside the evidence, which is done for the following three reasons:

20 Taking Photographs 1. With a fully labeled scale in the image, the viewer can get some sense of the size of the evidence. The size of some types of evidence cannot be appreciated without a scale. 2. With a scale in the image, it will be possible to enlarge the original image to life size so that it can be compared with a known item of evidence. 3. The labeling information on the scale helps document the image.

21 Taking Photographs

22 Sketches What is a crime scene sketch? A crime scene sketch is a permanent record of the relationship of items at the scene to each other and to help supplement photographs They depict the overall layout of the location more easily than can be accomplished by photographs. Sketches also allow for selectivity A sketch can be drawn purposely to leave out extraneous or confusing details that would be recorded in a photograph.

23 Sketches What is a crime scene sketch? Crime scene sketches can provide a record of conditions that are not readily recorded by other means. Distances can be shown over a large area and topography can be easily illustrated. Paths taken by subjects or vehicles can be demonstrated on drawings more easily than on photographs Sketches combine the best features of photographs and crime scene notes.

24 Sketches Types of crime scene sketches Rough sketches Done while on-scene Not done to scale Usually drawn in pencil Crude crime scene layout with measurements Final sketches Finished rendition of the rough sketch Does not include measurements Done in ink/computer Includes a title, legend, compass arrow

25 Sketches

26 Sketches Final sketches Title name of the complainant, service #, location of offense, initials and badge number, date. Legend what do symbols within the sketch mean?

27 Sketches Four different crime scene perspectives can be represented in a sketch: Bird s eye or overhead view Most common form of crime scene sketch Looking down upon the scene from above Shows floor layout Does not represent heights of items of evidence on walls Elevation or side view. AKA: detailed sketch Three-dimensional (3-D) Exploded and cross-projection sketch

28 Sketches BIRD S EYE OR OVERHEAD VIEW

29 Sketches ELEVATION OR SIDE VIEW: AKA - DETAILED 13 9 A

30 Sketches EXPLODED OR CROSS-PROJECTION

31 Crime Scene Mapping Mapping = measurements/measuring Types of mapping/measuring: Baseline Rectangular coordinates Triangulation

32 Crime Scene Mapping Baseline Most basic, least accurate Quick, easy to use Useful in large areas. Ex: parking lots Measuring tape is laid down establishing the baseline Measurements are taken from the baseline at a 90 degree angle to a point on the item of evidence. Center of mass or nearest point to the baseline

33 Baseline Method Crime Scene Mapping

34 Crime Scene Mapping Rectangular Coordinates Utilizes two baselines instead of one Two measurements are taken to a point on an item Small item Large item Useful in confined spaces and smaller interior scenes

35 Rectangular Coordinates Crime Scene Mapping

36 Crime Scene Mapping Triangulation Most accurate method that does not make use of advanced technology Accuracy comes by way of two fixed points If the object is of a fixed or constant shape (firearm, item of furniture), then the object is measured to two points from two fixed points = 4 measurements If the object is of a variable shape or size (puddle of water, pool of blood), then the object is measured to an approximate center of mass. Examples of two fixed points Corners of a room Edge of doorframe Junction boxes (outlets, light switches)

37 Triangulation method Sketches

38 Assignment Read Chapters 1 and 2 in textbook Homework 1: Due Today - Visit the following websites, explore and write a paragraph on something you learned about each lab: Read the following article: