FKA 1 Flashcards
According to RCMP FIS policy, is ‘probability of Identification’ testimony permitted on comparisons (excluding fingerprint).
The allowable conclusions for physical comparisons are probability based. That being said, we are not trained to provide a number in terms of probability.
Precautions for mixing Potassium Thiocyanate for scene exhibits. What is it used for?
- Rubber gloves
- Safety glasses
- Lab coat
- Fume hood
-It is a development medium and reacts with iron in soil
First aid measures Diazafluoren-9-one
- Inhalation: Fresh air
- Swallowed: Rinse mouth water, drink lots of water
- Skin contact: Wash area with soap/mild detergent for ~15min
- Eye contact: Remove contact lenses, flush water until contamination ceases
How does digital camera capture an image
- The shutter release button triggers the shutter to lift allowing light to enter through the lens and strike the sensor
- Light is converted into electrical signals called pixels
- A pixel includes a colour value, size and location
- The image is stored in electronic format such as RAW, TIFF, or JPEG
What is PPI
Pixels Per Inch (resolution)
Measurement of pixel density in an image in digital form
What is DPI
Dots Per Inch (resolution)
Measurement of dot densit in an image in printed form
Difference between PPI & DPI
Both are reolution however DPI is in print PPI is on a screen. A higher number value is needed for good clarity in printed format
What is CMOS
Complimentary Metal-Oxide Semicinductor
-Type of sensor used in digital photography
Describe contrast of an image in regards to digital photography
The tonal difference between the light and dark areas in an image
What is digital noise and the effect on an image
Coloured dots in an image, caused by long exposure times, high ISO setting or other factors such as temperature (rarely)
What is red eye in photography
When a subjects eyes appear red. It is caused by the reflection of light on blood vessels at the back of the eye.
What are artifacts in digital photography
undesirable changes to a digital image such as digital noise of chromatic aberation.
What are the tonal ranges of a digital photograph
Highlights -bright areas, midtones -(self-explanatory) and shadows- dark areas
Why is the use of a flash useful in daylight
Fill light can be used to illuminate dark or shadowed areas of interest
Using a digital camera, name 2 ways of correcting the white balance when the auto setting doesnt accurately record the colours of items
1) custom white balance using a grey card
2) Adjust the white balance setting to the appropriate light setting
- Incandescent, fluorescent, daylight, cloudy or shade
What types of forensic light source and/or lasers are available at your FIS section and what is the recommended level of eye protection for each?
Coherent tracer (laser - 532nm) Eye protection required is laser specific orange
Crimescope: The crimescope emits a variety of wavelengths from ultra violet to infrared the required eye protection are as follows:
300-400 clear,
415-445 nm yellow,
455-515 nm orange,
535 -550 red,
Infrared none
Polylight Flare 505 nm requires orange or red
Rofin Polylight UV 360 - clear
Rofin Polylight 415 - yellow
Rofin Polylight 450 - Orange
Rofin Polylight 530 - Red
How do you ensure the retention of the integrity of digital photographs obtained at a crime scene
- All images recorded consecutively & continuously
- no images are ever deleted
- All images are downloaded to folder ‘originals’
- All images stored on archival quality write-once CD-R or DVD-R
- Stored in KME
To photographically record a crime scene, what minimum two standards must your digital camera be able to provide?
Minimum resolution of 10 mega pixels and RAW capability
What are the standard items of PPE for safe guard at many crimes scenes
The basic items are gloves and a mask while using powders; also available is a mylar suit and booties. The level of PPE will be determined by the hazards present.
List four problems that may occur if the crime scene is not properly secured or protected
1) Destruction of material or evidence
2) Addition of material
3) Evidence could be moved
4) Loss of continuity making evidence inadmissable in court
Five basic patterns used to search a crime scene
1) Circle or spiral method
- beginning at a point on the perimeter, moving through the scene using a spiral pattern. Can utilize 1 to 2 persons
2) Strip/line method
- Area is divided into functional strips/lanes
- Strip: beginning at either end, searcher moves down the strip and reverses direction at the end of each strip (1-2 persons)
- Line: beginning at either end, a line of searchers moves down the line in a continuous single direction (larger group)
3) Grid method
- Similar to strip and search, area is divided into functional strips, then subdivided at 90° angles to each other. The search starts at the outer most strip and move up and down similar to strip method
4) Quadrant/ zone method
- variant 1: Confined spaces, areas not easily search by patterned movement. Good for vehicles, breaking down each area into a zone and label
- variant 2: Larger scene. Area is divided into quadrants/zones which can then be searched using another search method. Can assist in triangulation method of measuring locations of exhibits or items of interest by first properly staking and measuring the quadrants/zones
5) point to point
- Searcher determines what order they choose to deal with primary focal points and evidence. The path is clear to the first focal point, then immediately around it. Path is then cleared to the next focal point, so on and so forth until scene is complete
Upon arrival to a crime scene what order would you conduct the investigation
1) Obtain info from investigator
2) Conduct a scene survey and establish a safe path
3) photograph crime scene
4) Examine the exterior for evidence
5) Examine interior for evidence
6) Photograph the individual pieces of evidence seized
7) Prepare a report and advise investigator
