cte forensic science 1- 2 unit 2/8 recording the crime scene

CTE Forensic Science 1-2

Unit 2/8

Recording the Crime Scene

© 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved

Learning Standards and Objectives

CTE: 4.0 = Compare/Contrast Safety Precautions & Procedures in Law, Public Safety, & Security (4.1); 6.0 = Analyze Investigative Procedures (6.1 - 6.7); Science: Strand 1 - Concept 1 PO 1 - 4; Concept 2 PO 1 - 5; Concept 4 PO 1 – 4

STUDENTS WILL BE ABLE TO:

Evaluate crime scene preservation. Evaluate the process of crime scene investigation, recording the Crime scene.

MEASUREMENTS:

Quizzes, class discussions, comprehension assessments

performance assessments (labs).

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Key Terms – Be prepared for a QuizDocumentation Lossy and Lossless Compression

Personnel Log Rectangular Coordinates

Digital Photography Baseline Method

Camera Lens Triangular Method

Camera Filters (Barrier & Bypass)/ Compass Point Method

Aperture and Shutter Speed/ Cross Projection Method

Depth of Field Polar Projection Method

Illumination Rough Draft

Tripods Final Draft

4 Corners CAD

Doll Hours Murders

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Crime Scene Notes

Note-taking begins when the investigator is contacted and requested to report to the crime scene.

The crime scene notes should begin with writing:

1)The identity of the person who contacted the investigator

2) Time of contact and arrival at the crime scene

3) Preliminary case information

4) Personnel present on arrival

and those being contacted


Crime Scene Notes

• Notes contain a personnel log, all observations made by the investigator, and the time observations were made.

• Notes are taken in an orderly format, written at the same time as observations are being made.

• Notes are written in a small notebook in blue or black ink


Crime Scene Notes

Investigators may choose to record crime scene notes on audio tapes.

• This leaves the hands free to process the scene as the notes are taken.

• Tape-recorded notes must eventually be transcribed to a written document.

Comprehension Assessment:

What happens to everything recorded at a crime scene?

Why is it so important to keep all recordings and be professional?


Photography

Photographs taken at a crime scene:1) Show the layout of the crime scene

2) Show the position of collected and uncollected evidence

3) Show the point of view of victims, suspects, and witnesses

4) Show the original condition of items of evidence at the scene

• Film consists of a sheet of silver halide grains which “expose” when exposed to light.

• Film speed is a measure of the light-gathering capacity of the film.

• Special types of film include Polaroid film and Infrared film.

http://www.gigapixel.com/image/gigapan-canucks-ra.html

Write at the top of the top of the page labeled Film Photography.


PHOTOGRAPHY

http://youtu.be/cf3ZHWeeoo0

http://youtu.be/5Il8vtzlciw


Digital Photography

• Digital photography - light-sensitive microchip captures light on each of millions of tiny picture elements, called pixels.

• Light is recorded on each pixel as a specific electric charge which is read by the camera as image information which is stored as a file on a memory card.

• The number of pixels is directly related to the resolution of the picture. Photographs with more pixels show increasingly good resolution, or more detail and sharpness in photographs.

• The number of pixels that a camera features is usually measured in millions of pixels, or megapixels.


Cameras

• Most commonly used camera at crime scenes is the Single Lens Reflex (SLR) camera or the Digital Single Lens Reflex (DSLR) camera.

• SLR and DSLR cameras allow for the use of various accessories such as lenses, flashes, and filters.

• SLR and DSLR cameras also allow for manual adjustment of camera settings, such as aperture and shutter speed, that affect image quality.


DSLR Modes

• “auto mode” automatically selects an appropriate f-stop and shutter speed

• “sports mode” captures subjects in motion by using a (faster) shutter speed.

• “night mode” uses a lower (slower) shutter speed to gather as much light as possible.

• “landscape mode” automatically selects higher f-stops to improve depth.

• “portrait mode” selects lower f-stops to make the subject stand out clearly


Lenses

• The camera lens bends light to focus an image on the film or digital microchip.

• The lens’s focal length, the distance between the lens and the image projected on the film or microchip, determines the area shown in the resulting photograph.

Write the following information next to BIG LENSE PIC

• Normal Lens –Focal length of 50-55m – Used for most photographs that need to be taken at a

crime scene because it can show as much area as half a wall


Filters

• Barrier filters block one (color) of light from reaching the film or microchip, making areas of that color appear lighter in the photograph.

• Bypass filters allow only a small range of wavelengths of light to reach the film or microchip and block all others.


Lenses

Telephoto Lens• Focal length of 100 mm or greater • Used to magnify images

Wide-angle Lens• Focal length of 35 mm • Used to show much more area in one photograph than a

normal lens Macro Lens• Focal length of less than 50 mm

• Used for highly-detailed close-up photographs Multi-purpose Lens• Focal length from 28-80 mm used to take normal, wide-angle,

and telephoto photographs


Aperture and Shutter Speed

• The camera aperture is a measure of the diameter of the opening of the diaphragm, which allows light to reach the film or microchip.

• On film or digital cameras, one adjusts the aperture by setting the f-number.

– The lower the f-number setting, the wider the aperture and the more light is allowed in.

• The shutter speed is the length of time that the film or microchip is exposed to light.

• The shutter speed is measured as a fraction of a second by factors of 1/2 (i.e. 1/2, 1/4, 1/8, etc.).


Depth of Field

• The depth of field shown in a photograph is the amount of area in the foreground and background of an object in focus that is also relatively in focus.

• The smaller the aperture opening, the greater the depth of field will be. >A=<DF

• Higher f-number settings will yield higher depth of field. +F <> +DF


Illumination

• The color temperature of a light source is “hot” if it has a bluer hue, while a “cold” light source has a red-orange hue.

• Light meters on film or digital cameras allow photographers to measure the amount of light in a shot.

• A flash unit can produce either direct reflective lighting or oblique lighting, which is achieved by positioning the flash at an angle less than 90° to the surface to show detail.


Tripods

Using a tripod eliminates the possibility of blurred photos resulting from unsteady hands.

For crime scene photography, it is useful if the tripod has:

1) Independently adjustable legs suitable for uneven terrain

2) A level to ensure 90º images of evidence


Crime Scene Photography Log

A detailed log of each photograph taken at the crime scene is kept by the crime scene photographer.

The top of the photography log form includes:

• Case number

• Type of scene

• Date

• Location of scene

• Description of the camera and lenses being used

• Film type and speed (if applicable)

• The photographer’s name and title

James O'Sullivan

If possible add a photo of a Crime Scene photography log. Would be easier for the students to understand.


Crime Scene Photography Log

For each photograph, the log records:

• Date and time the photograph was taken

• The location of the picture

• The f-stop and shutter speed settings

• The lighting used and the lighting angle (if applicable)

• A brief description of the subject of the picture


Who cares if the log has all this basic information?


Basic Guidelines

1. Photograph scene in unaltered condition

2. Fill the frame

3. Avoid shadows in the photograph

4. Maximize depth of field

5. Photograph scene in a logical sequenceOutside, Entry, 4 Corners, Up, Down,

All around (1st photograph all prior to numbering evidence and again in numbered order)

6. Keep a log of all Photographs (in order)


Crime Scene Photography

Four minimum photographs required at a crime scene are:

1. An overview photograph

2. A medium range photograph

3. A close-up photograph

4. A close-up photograph with a scale

ADD: Location, weather, time, 4 corners, find with picture and photo in order, document with log.



Overview photographs of the entire scene and surrounding area, including points of exit and entry, are taken first.

• Taken from the outside borders of the scene and from various angles

• If the crime scene includes a body, photographs must show the body’s position and location relative to the entire scene.

• Include a “visual tag,” an object recorded in multiple overview photographs, to help visually piece the scene together.



Medium-range photographs show the layout of smaller significant areas of the crime scene.

• Taken with evidence markers in place to show the spatial relationships between and among pieces of evidence in greater detail than the overview photographs.

• Include at least one photograph of the “center” of the scene.

• In violent crimes, this usually includes the site where the victim was found and the surrounding area.



Close-up photographs are taken last and show greater detail of individual objects or evidence.

• Taken at a 90º angle to the object, with and without evidence markers and scales.

• Scales should be placed as close to the evidence as possible without affecting it in any way.

• After the 90º photographs have been taken, photographs from other angles may be taken.

• The most important close-up photographs are those depicting injuries and weapons lying near a body.

• After the body is removed from the scene, the surface beneath the body should be photographed.


Special Crime Scene Photography

• Night photography requires the use of external lighting or “painting with light.”

• Indoor photography requires photographs of the neighborhood, points of entry and exit, and all walls, floors, and ceilings.

• Outdoor photography requires location of photographs to be recorded by a Global Positioning Device or measurements from landmarks.

– May include aerial photographs

James O'Sullivan

If possible add examples of the various types of Special Crime Scene Photography



• Arson photography requires photographs of the point of the fire’s origin and use of special equipment or techniques to provide maximum contrast in photographs of charred areas.

– May also include photographs of crowd outside scene because arsonists commonly return to scene

• Sexual assault photography requires photographs of all wounds and clothing while showing discretion to the victim.

• Impression photography requires oblique lighting to show details and a scale to later create a 1:1 scale photograph for comparison to footwear or tire samples.



• Bloodstain photography requires photographs of all pertinent stains and determined area of convergence or area of origin.

– Bloodstains treated with luminol photographed in complete darkness

• Latent fingerprint photography require photographs with a 1:1 scale using a special latent fingerprint camera or a regular camera fitted with an adapter.

– Black and white film used to show greater contrast


Digital Crime Scene Photography

• Digital images are easily manipulated using computer programs and may not show an accurate depiction of the crime scene.

• Digital images may lose image data or details through compression.

• Digital images are preserved by either lossy or lossless compression.

– Lossy compression condenses files by discarding some image information. The information lost during this compression is irretrievable.

– Lossless compression condenses files without discarding information so no important image information is lost. For this reason, all digital crime scene photographs should be saved by lossless compression to avoid losing any important information contained in those images.


Digital Crime Scene Photography

Law enforcement agencies ensure the admissibility of digital crime scene photographs by:

• Developing Standard Operating Procedures that must be followed

• Saving images to writable (not rewritable) disks by lossless compression

• Saving enhanced or altered images as separate files• Keeping a detailed and accurate photography log• Submitting testimony from the crime scene

photographer as to the accuracy of the digital images

Comprehension Assessment:Why are all photographs legal evidence?


Videotaping Crime Scenes

• As with still crime scene photography, the crime scene video must include overview, medium-range, and close-up images.

• A narrated crime scene video combines photography and notes.

– However, it is important that only one person narrates and no side conversations are captured on the video.

• Some video cameras can produce still photographs, but the quality is often poor.

– Therefore, still photographs from a film or digital camera are still required.


Sketching the Crime Scene

Crime scene sketches (measurement)1) Clearly show the layout of a crime scene (NORTH DIRECTION AT TOP)

2) Illustrate the relationship in space of all significant items and features (always measure from fixed locations)

3) Clarify (PLOT objects and features) already described in notes or shown in photographs

4) Show measurements over long distances and topography of outdoor scenes (UNITS OF MEASUREMENTS – INCHES, FEET, CENTIMETERS, METERS) and measure from FIXED locations.

5) Depict possible paths of entry, exit, and movement through the scene; Demonstrate whether the account of a victim, suspect, or witness is feasible

6) Make a Legend (case number, type of crime, investigator, persons assisting, direction of north, Identify information in sketch/key, Scale.

Write on bottom of star graph: MATERIALS NEEDED TO SKETCH

GRAPH PAPER, PENCIL, MEASURING TAPES (STEEL IS BEST), RULER, COMPASS


Rectangular Coordinates

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Baseline Method

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Triangulation method

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Compass Point Method

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Cross – Projection Method

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The Rough Crime Scene Sketch• Rough sketch is the first pencil-drawn outline of the scene and

the location of objects and evidence within this outline. Usually not drawn to scale, Although distances are measured and indicated in the sketch

• Sketch WHILE photographs are taken and before anything is moved. Sketch as much as possible.

• The current standard method utilizes Computer-Aided Drafting (CAD) programs to create the finished sketch. CAD programs also allow for the creation of three-dimensional finished sketches.


How can a Defense Attorney create reasonable doubt in the minds of the jury in court based on the use of CAD?


The Finished Crime Scene Sketch

1. A rough sketch is created at the crime scene and contains an accurate depiction of the dimensions of the scene and shows the location of all pertinent objects and features.

All rough sketches include

2. Title block with information on the case, crime scene, and

person creating the sketch

3. Legend with identity and dimensions of objects in the sketch

4. Compass showing the North direction

5. Body containing the sketch itself

6. Points of reference for objects can be shown by the rectangular, triangulation, baseline, cross projection or polar coordinates methods.


LAB - C.S.I First Responder Interview

Students will be able to ask information of the SRO concerning the Mock Robbery scene.

Students will not be prompted during the 1st run.

Students will do a second interview (as a class) concerning a Mock Homicide scene.

Students will learn to ask the appropriate questions in the appropriate order during this exercise.

NOTE: Make sure all students are asking questions in order so as all students are held accountable for asking questions.

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LAB - Photography

Class will examine crime scene photos

www.huffingtonpost.com/2013/01/04/jodi-arias-crime-scene... Cached

Jodi Arias Crime Scene Photos (GRAPHIC)

DISCUSS THE ANGELS, LIGHT, EFFECTIVENESS FOR THE AJUDICATION PROCESS AND MORE.

STUDENTS WILL TAKE PICTURES OF THE CLASSROOM,( NOT OF STUDENTS) TO LEARN A SYSTEMATIC PROCESS

LOCATION, WEATHER, TIME, 4 CORNERS, UP DOWN, WIDE – CLOSE UP, FIND EVIDENCE BY PHOTO, PHOTO NUMBERED EVIDENCE IN ORDER.

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LAB - MEASUREMENTS

• Each Team will receive 1 toy metal car and red string.

• Students will be expected to set up the car in several positions on the table as to simulate a location of a car in a parking lot, street, alley, driveway and against a solid object.

• Students will be expected to use the red string to measure the toy car using the Rectangular, Baseline, Triangulation, Compass Point Methods of measurements.

• Students will be expected to document their layouts and measurements for accuracy.

• Students may measure the classroom

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LAB - Sketching a C.S.

Using Crime scene (police graph paper)

• Students are expected to document the layout of the classroom to scale on graph paper. They may measure the main items in the classroom.

• Do not include anything in the room but the room, openings, large furniture and desks.

Box top Year Long Assignment - View clip or film.

http://youtu.be/Ej6vWZh3_kw

Instructions for this lab will be provided in written format.

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cte forensic science 1- 2 unit 2/8 recording the crime scene

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