Discussion Question

Documentation is an important form of crime scene work. What are the different forms of documentation? What are the types of photographs needed in documenting crime scenes? Why sketches are an important form of documenting crime scenes and the important elements that must be included in the sketch.

Sketching

Sketching
Consider sketching to be a floor plan of your scene.
Bird’s eye view (a bird flying over head looking straight down).
Objects, furniture are two dimensional (wide and long) but all are flat (we do not see the legs of furniture for example).
Present a visual aid for where objects, evidence, rooms are located.

Sketches done at the time of the crime scene processing are called rough sketches. These contain the measurements.
A final sketch is cleaned up and without the dimensions on it but the sketch is drawn with those dimensions in mind (example using graph paper if a room is 10 feet by 20 feet in width and length by using 10 squares on grids paper you are drawing the room to its measured size).

Some points
Sketches are two dimensional (width and length).
Drawn as if we are a bird flying over head looking straight down. That means we do not see as if we are standing in the room.
Write in one direction
Have a north directional. Put north at the top of the sketch
Label furniture and areas
Give evidence letters or numbers
Have a legend on the front with the sketch denoting what the letters or numbers means on the sketch. Do not draw shapes.
Keep it simple. Do not have an overwhelming amount of letters.
If you do not have a standard template for the victim or body just write the word victim.
Keep the main thing the main thing.

D
B
A
C
Victim
http://www.forensicmag.com/articles/2014/01/crime-scene-diagramming-back-basics
Legend
A- 9mm FM gun serial #1234
B- 9mm R&P casing
C- 9mm R&P casing
D- possible blood drops
Homicide
04-12-2015
12345 NW King street
Sketch by SPlotkin #253
Not to scale

Final sketch
Courtesy of Jorge Hernandez

Exploded view sketch used when depicting critical evidence on walls. Think of a cardboard box and opening the sides and lying them down…

Computer Sketching Program with Flex-man
Title block
With case
info

Clandestine graves need two views
Bird’s eye

Clandestine graves need two views
Side view

Be sure to include heading (case information)
Diagram area
Legend denoting what your letters or numbers are on the sketch. Do not try and draw objects.
North directional (try and always have north on top).
Also by writing the word victim rather than drawing a body takes away any prejudice or bias.
Not to scale recognizes a degree of error inherent in human beings when taking measurements.

Types of measurements in sketching
Rectangular coordinates- using two permanent walls (exterior which are 10 inches thick rather than interior walls which are 5 inches thick).
Do not use opposite walls. Use an east/ north wall or a south/ west wall when taking measurements and use same two walls to measure everything in that room.

Triangulation
Used when measuring from the corners of a room. The important thing to remember is at what angle you measured as objects may not be in the center of the room.

Baseline coordinates
Great for outdoor use when using a permanent point such as a lamp post (be sure to get lamp post information).
Measure from your lateral line east to west and north to south. Use two tape measures.

Lamp post
North

Grid coordinates
Both rectangular coordinates and triangulation can be used with this.
Used when crime scene is outdoors (burial sites, scattered remains).
A grid is created.
Set a datum, extend a baseline out to the right and up, creating three corners.
Verify the two sides are at right angles using the 3-4-5 rule.
Set the final corner and square it to the opposite sides.
Ross Gardner Practical Crime Scene Processing, CRC Press

image1

image2

image3

image4

image5

image6

image7

image8

Crime Scene Investigation and Reconstruction

Fourth edition

Chapter 3

Crime Scene Photography

Objectives of Crime Scene Photography
Record the condition of the scene before alterations occur
Record the location and position of evidence items collected
Document the point of view of principals and potential witnesses
Document spatial relationships of pertinent items

Photography is…
Not a substitute for notes or sketches

An essential supplement to other modes of crime scene documentation

Crime Scene Photography
Photography also plays an important role in the efforts to reconstruct the events of the crime. In conjunction with sketches, photographs capture the physical aspects of evidence at the crime scene that are amenable to reconstruction by a qualified professional.
Capture the physical aspects of evidence at the crime scene

Issues
How many photographs to take?
Conditions at the scene create photography challenges:
Big outdoor crime scenes
Small crime scenes like bathrooms
Lighting issues like complete darkness
Smoke, fog, rain, etc.

A standard operating procedure should also be in place for all digital photography.

Cameras for Crime Scene Photography
The type of camera best suited for crime scene photography is the single lens reflex (SLR)
Important to have zoom lenses with macro capabilities
35mm is being replaced with digital single lens reflex (DSLR) cameras

Videotaping Advantages/Disadvantages
Advantages:
Provides a lifelike view to the viewer
The ability to instantly review the videotape at the scene
Disadvantages:
The addition of unnecessary detail
Lower resolution of the video camera as opposed to that of a still camera

Systematic Approach
To ensure that all necessary photographs are taken at the scene prior to any actions that may compromise the integrity of the scene

The sequence should be done by working from the perimeter to the center
This will facilitate the presentation of the photographs in the courtroom

Log all photographs taken in a photo log

Types of Photographs
Overview or layout (long range)
Medium range
Close-up
Point of view of witnesses
Night photographs
Latent impressions
Wounds

Position of Camera “Normal” to a Surface

Three Factors in Photography
To produce sharp images in the photograph, you need:
High quality lenses
High resolution of the image sensor in digital cameras
The correct exposure by the camera

Basic Camera Information
The Light Meter and Exposure—measures the brightness of available light
Lighting—flash cube, electronic flash, strobe etc.
Filters—used to provide special effects or eliminate unwanted glare

Camera Basics
Lens
Focal Length
Relates to depth of field
Determines if lens is wide angle or telephoto
Compound Lenses
Light passes through a series of “elements”

Camera Basics
The shutter – two basic types of shutter mechanisms:
The focal plane shutter, positioned just in front of the film
The leaf shutter, positioned either just inside the lens housing close to the diaphragm or behind the lens

The Shutter in Detail
The principal function of the shutter is to keep light from striking the film or image sensor in DSLRs
Shutter speeds marked on most modern cameras follow a sequence – 1, 2, 4, 8, 15, 30, 60, 125, 250, 500, 1000, 2000, etc.

Camera Basics
Several factors affect the amount of light reaching the film, principally the duration of the exposure and the diameter of the aperture.
The aperture is the opening in the lens
Calibrated in f-numbers
Common f/stops are f/1.8, f/2.8/, f/4,/ f/5.6, to f/22 or even f/32

The Aperture in Detail
Controls depth of field
f/22 has great depth of field while f/1.8 would result in a very shallow depth of field

The Aperture in Detail
Apertures can range from 1.2 to 22. The larger the f-stop, the smaller the aperture; the smaller the f-stop, the larger the aperture.
F/stops are really fractions, like shutter speeds. (f/22 is really 1/22)
f/22 f/5.6 f/1.8

Camera Shake
Camera shake (tremor, vibration) is the movement passed to the camera by involuntary hand and body tremor
This phenomenon can be minimized with
Long focal length lenses
Image stabilization (IS) in the lens (lens based) or camera body (body based)

Depth of Field
The zone both in front of and behind the focal plane that also appears acceptably sharp
Depth of field can be controlled because it is affected by changes in the aperture size

Digital Cameras
Digital cameras capture a digital image on a digital image sensor, also called an image processor
The image sensor is composed of pixels
A pixel is a single photosensitive unit (cell)
One megapixel equals one million pixels

Digital Cameras
Point-and-shoot digital cameras have a liquid crystal display (LCD) screen which acts as the view finder
DSLR cameras have an optical view finder and an LCD screen for viewing the captured images
The optical view finder is not affected by strong ambient lighting

Digital Cameras
Storage cards are of several types
The Secure Digital (SD) card -stores from one to eight megabytes
The secure Digital High Capacity (SDHC) card – stores from one to sixteen megabytes of memory

Digital Cameras – Image Resolution
Determined by:
Quality of the camera lens
Number of megapixels of the camera image sensor
In DSLR cameras, the image sensor is about 21.5 mm by 14.4 mm, larger than most point-and-shoot digital cameras

How to work with available light
When working in low-light situations, it is important to remember that our flash units can only travel a limited range, so we must work with light in the scene to assist us. If our eyes can see it then so can the camera.

ISO
Sutter Speed
Aperture (FStop)
The exposure triangle
Working with available light

Setting #1: sensitivity (known as the ISO)
ISO is the sensitivity of the sensor to the light. The higher this ISO setting, the more the sensitivity to light, thereby allowing that image sensor will work better in low-light conditions.
1. ISO (International Organization for Standardization [same as the old ASA, American Standards Association]): This speed value is based on an arithmetic scale.

A defect that occurs with too high of an ISO setting is called noise. When we used film cameras, this was known as graininess. Noise is the pixilation of the image that is seen when the image is enlarged and it appears to look like red and blue dots in the image. When photographing fingerprints, shoe wear, or other images, it is important that noise does not take away from the information or details of the evidence or scene being captured.

Setting #2: the shutter
There are two basic types of shutter mechanisms:
1. The focal plane shutter, which is positioned just in front of the sensor (hence the name) and is used almost exclusively in SLRs.
2. The leaf shutter, which is positioned either just inside the lens housing close to the diaphragm (in the case of the compound lens) or behind the lens (in the case of a simple lens).

The shutter speed is also known as the curtain. This is controlled in the camera. When we push down the button to take a photograph, the sound that is heard is the shutter. Shutter speeds are observed in fractions. So, when 500 is displayed, this really means 1/500. The faster the shutter speed, the less light you allow in.

A defect with too slow of a shutter speed is that we experience camera shake. The human hand can hold the camera steady for 1/50th of a second without camera shake (blurry images). Camera shake (tremor, vibration) is the movement passed to the camera by involuntary hand and body tremors, causing less sharp photographs.

Setting #3: the aperture/F-Stop
The aperture, also known as the F-stop (seen as an F with a number on the display, i.e., F4.0), is the opening in the diaphragm that determines the amount of light passing through the lens.

The range of apertures is 2.8–22 depending on the focal length of the lens. The higher the aperture setting, however, the less light you allow in and the more you close down the diaphragm opening (F22 lets in less light than F8).

It is important to note here that depth of field is directly affected by the aperture setting.

Depth of field
When a lens is focused on a point a certain distance away, there will be a zone both in front of and behind this point that also appears acceptably sharp on the film; this zone is called the “depth of field.”

Depth of field can be controlled because it is affected by changes in the aperture size.
With the aperture fully open F2.8), a lens has a small depth of field, and the further the lens is stopped down, the more the depth of field (F22).

Depth of field refers to the area that is in focus from lens to subject matter. The smaller aperture/F-stop number (f/2.8) correlates with a larger or wider aperture size, which results in a shallow depth of field. The larger aperture/F-stop number (F22) results in a smaller aperture size and therefore a deeper depth of field.

Latent fingerprints and patent impressions
Should always be photographed prior to lifting (without and with scales).
Use arrow directional in photographs.
Shoot photographs in the RAW format.

Photography of Wounds

Wounds should be photographed both before and after cleansing of the wound by medical personnel in the case of a living subject or by the forensic pathologist in the case of a deceased subject.
The wound site(s) and periphery should be searched thoroughly for any trace evidence before cleansing.

Infrared Photography
Uses infrared filters, which records images formed by infrared light
Used to locate alterations on documents
In aerial photographs it helps to locate gravesites
In the crime lab it is used to detect and document gunshot residue on bloody or dark fabrics

Infrared photography
Infrared photography uses designated infrared cameras or filters, which records images formed by infrared light.

Infrared photography is used in questioned document photography to locate and document alterations on documents, in aerial photography to assist in locating gravesites, and in the crime laboratory to detect and document gunshot residues on bloody or dark fabrics.

Ultraviolet Photography
Used to document materials that glow under ultraviolet light such as semen, certain fibers, and latent fingerprints dusted with fluorescent powders
Also used to photograph body wounds such as bitemarks

Additional photographic techniques
How to paint with light
Luminol/ Bluestar photography

QUESTIONS?

image2

image1

image3

image4

image5

Crime Scene Investigation and Reconstruction

Fourth edition

Chapter 4

Crime Scene Sketches

Value of Sketches
An essential supplement to the investigator’s notes and photographs
Provide precision with regard to spatial relationships of items seen
Provide a visual model to illustrate the investigator’s testimony in court

Objectives of Crime Scene Sketches
Present a clear “mind’s eye” picture of the scene
Complement the investigator’s notes and photographs
Show the accurate location and relationships of the evidence items

Objectives of Crime Scene Sketches
Refresh the memory of the investigators
Illustrate the testimony of witnesses
Provide factual data for crime scene reconstruction

Rules of Thumb for Sketches
Plan systematically for sketching the scene
First roughly show the overall layout of the scene
Prepare detailed sketches of pertinent area with measurements
Prepare blowup sketches as necessary
Additional sketches

Points to Keep in Mind
Show compass point on sketch
Make accurate measurements for all evidence items
Use equal accuracy for measurements for items on the same sketch
Use fundamental methods for measurements
Make sure that the tape is straight and does not sag when the measurement is taken
Have two individuals verify all measurements

Avoid Common Errors
Reading numbers upside down
Reading the wrong foot mark
Confusing the zero point of the tape
Reading tenths of a foot for inches

Rough Sketches
The detailed sketch is what the term “sketch” or “diagram” usually refers to when referencing a crime scene sketch
This sketch is hand drawn at the scene
Contains measurements for all evidence item locations and other pertinent objects such as furniture

Rough Sketches
The locality layout illustrates the general area in which the crime scene occurs
Designed to provide an overview of the crime scene

Locality Layout Sketch

Small Area Sketches

The Blowup Sketch
Allows for higher accuracy of measurements for blood spatters, bullet trajectories, or other pattern evidence
Blowup sketches are detailed sketches of small areas inside a larger sketch

Blowup Sketch

Exploded View Sketches
Used to illustrate the interrelationships of blood spatters, bullet holes, and trajectories or other patterns of significance
Shows the walls (and occasionally the ceiling) lying flat (folded down)

Elevation Sketches
Show the slopes present in the scene
Are rough sketches made in order to show the elevation perspective of a crime scene
An elevation drawing is a rough representation of the terrain without elevation measurements and is a supplement to photographs

Elevation Sketches

Finished Sketches
Finished sketch (not to scale)
Finished sketch (drawn to scale)

Not to Scale Sketch

Critical Accuracy
Manually drawn sketches

Professionally drawn sketches

Computer-drawn sketches

Computer-Drawn Sketch

Courtroom Display Sketches
For courtroom display purposes only
Represent a wide variety of sketches
Simple sketch drawn to scale
A very large drawing in color
Prepared by an architect or a professional graphics artist; or, in some cases, they may be computer-drawn

Three-dimensional Computer Drawn Sketches
Are especially helpful to the individual preparing a crime scene reconstruction
Permit viewing of the scene from a number of different aspects, from side views at differing angles to overhead viewing

Preparation: Suggested Procedure
Should follow the same sequence followed in the initial survey of the scene
The crime scene investigator should first prepare the layout sketch in order to provide a framework
A rough sketch should be prepared for each area containing pertinent objects or evidence

Preparing the Sketches
Measure dimensions of each area accurately
Two individuals should verify all measurements
Each evidence item requires measurements to at least two fixed points

Preparing the Sketches
Measure the dimensions and location of furniture and other objects pertinent to the scene
Measure the location of windows and doors; show the direction of the door opening
Label furniture and other objects with letters

Preparing the Sketches
Label evidence items with numerals; and place labeled items in the legend with their measurements
Check each sketch for accuracy and completeness

Measurement Techniques
Rectangular coordinates measurement method
Triangulation measurement method
Secondary reference points measurement method
Transecting baseline measurement
Polar coordinates measuring method – Software mapping technique

Rectangular Coordinates Method

Triangulation Method

Transecting Baseline Method

Polar Coordinates Method

Mapping Technique Method

Personnel Requirements
A three person team is the most efficient approach for preparation of sketches
One prepares the sketches while the other two take measurements

Equipment Needed
Tape measures- metal are preferred because they are the most accurate, sag the least and are the easiest to handle
Sketching materials- writing materials, paper, straight edge, and clipboard
Compass for triangulation

QUESTIONS?

image2

image1

image3

image4

image5

image6

image7

image8

image9

image10

image11

image12

image13

image14

image15

Turn in your highest-quality paper
Get a qualified writer to help you with

“ Discussion Question ”

Get high-quality paper

Guarantee! All work is written by expert writers!

Still stressed from student homework?

Get quality assistance from academic writers!

Order now