FKA 1 Flashcards
According to RCMP FIS policy, is ‘probability of Identification’ is permitted on comparisons (excluding fingerprint).
We are not allowed to provide probability. We have determined opinions we can provide for physical match and impressions.
5 for footwear impressions and 4 for physical match.
Precautions for mixing Potassium Thiocyanate for scene exhibits.
- Rubber gloves
- Safety glasses
- Lab coat
- Fume hood
- Eye/skin irritatant
- Wash with mild soap/water 15min
- Maintain personal hygiene after exam/before meals
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
- Aperature opens front of camera
- Light enters through lens
- Brought into sharp focus on an image sensor (CCD or CMOS)
- Light converted into electrical signals called pixels
- Pixels are digital squares composed of a number based on the intensity of light rec from sensor
- Electronic image stored in electronic format such as RAW, TIFF, or JPEG
What is PPI
Pixels Per Inch
Measurement of pixel density (resolution) of an electronic image, contains a series of #’s which describes its colour or density
What is DPI
Dots Per Inch
Unit of measure in which the # of dots can be placed in a line in a space of 1 inch
Difference between PPI & DPI
DPI = Dots per inch PPI = Dots per inch
A given DPI does not always have the same resolution as often move dots are required to create a single pixel, which varies from device to device.
What is CMOS
Complimentary Metal-Oxide Semicinductor
-Type of sensor used in digital photography
Describe contrast of an image in regards to digital photography
Difference between the darkest and lightest areas of an image
Greater the difference, the higher the contrast
What is digital noise and the effect on an image
The degradation of a digital image which can appear as ‘speckles’ on a photo.
Caused by long exposure times, high ISO setting or other factors such as temperature
What is red eye in photography
Caused by flash which glares back from the subjects pupils.
Caused as a result of high density of blood vessels directly behind the pupils at the back of the eye
What are artifacts in digital photography
Caused by the sensor, undesirable changes to a digital image
What are the tonal ranges of a digital photograph
1) Highlight
- Bright areas within a photo that still maintain detail
2) Shadow
- Darker areas of the image that still maintain detail
3) Mid-tones
- Neither shadows or highlights; middle value of luminance
Why is the use of a flash useful in daylight
Reduce harsh shadows from strong sunlight
Fill flash 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) Grey card reading
2) Adjust the white balance setting to the appropriate light setting
- Incandescent, fluorescent, daylight
Formula to determine the maximum printed size to create a ‘good’ quality print of digital image
Divide the image size in pixels by 300
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?
1) Minimum resolution of six mega pixels
2) Ability to capture RAW images
What are the standard items of PPE for safe guard at many crimes scenes
Gloves, mask, glasses, Mylar suit, booties, issued pants, long sleeves (when applicable)
List four problems that may occur if the crime scene is not properly secured or protected
1) Unknown persons may destroy evidence
2) loss of continuity of evidence
3) evidence could be hidden or removed
4) evidence may be deemed in admissible 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 surgery 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 seen. 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) Take notes of location, persons present date/time
2) obtain information from investigator and conducted a survey of scene
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