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Shutter speed
- the length of time that the film/microchip is exposed to light
- fractions of a second vs 1 second
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bulb setting
shutter stays open as long as you want it open
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depth of field
the amount of area in the foreground and background of an object in focus smaller aperture (F/22)-=greater depth of field in focus
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flashes
- supplies artificial light
- 1. direct
- 2. bounce
- 3. oblique < 45 degrees show greater detail with shadowing
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filters
helps to enhance specific elements of the picture by allowing certain wavelengths to reach the film
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1. overall
2. medium
3. close-up
3 types of photographs
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overall photographs
- exterior of residence car
- door windows
- general terrain
- rooms- over lap and shoot from 4 corners to get a full view
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Medium
- evidence establishing shots
- a piece of evidence is framed with some obvious landmark located in an over shot
- gives viewer an idea of where the item is located
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close-up
photo goal is to provide detail identifying marks, shape (need scale)
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video
- adds to photographs not replacement
- great for juries....place them at the scene
- move slowly
- turn off microphone
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Crime scene sketch
- serves as a grapher representation of the scene showing layout orientation and relationships
- 1. rough
- 2. finished
- hand drawn with rules
- computer aided
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sketch
- include location of doors, windows, furniture, victims, evidence and any important items
- dimensions of rooms
- need title block
- victims name , date, address location, name of artist case #
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Birds- eye view
only horizontal surfaces are represented
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exploded view
same as birds eye view but the walls are collapsed good for evidence located on walls
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3D view
view done with computer
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Crime Scene mapping
defines the size of the scene and where in the scene items are located
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1. rectangular coordinated
2. triangular
3. baseline
4. polar coordinates
5. total station mapping
5 measuring methods
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rectangular coordinates
two distances to an object at right angles
-
triangular
measure the distance to an object from fixed points
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baseline
- measuring tape from two fixed spots and then second measurement at 90 degrees
- used in accidents
-
polar coordinates
one reference point is used with distance and direction (angle) using a compass
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total station mapping
electronic device that measures distances, angles, and heights
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collect evidence
perform additional processing techniques once evidence is removed
things that could damage evidence
debrief
Final steps at the scene
-
physical evidence
- any object that can establish a crime has been committed or that can link a crime and its victims or perpetrator
- must recognize it
- collect it properly
- package it correctly
-
contamination
- the transfer of extraneous matter between the collector and the evidence
- eg tracking in fibers from your house
-
cross-contamination
the transfer of matter between two or more pieces of evidence
-
chain of custody
a list of all people who came into possession of an item of evidence
-
standard/reference
physical evidence whose origins is known, such as blood or hair from a suspect that can be compared to crime-scene evidence
-
collected=>crime lab=>document=>analyzed =>report written
submitting evidence procedure
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identification
the process of determining a substance physical or chemical identity (e.g. cocaine, TNT, blood, seman, species)
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process of identification
- adoption of testing procedure
- number and type of tests much be sufficient to exclude all other substances
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comparison
- the process of acertaing whether two or more objects have a common origin
- suspect specimen vs. standard/reference specimen ( paint chip from hit and run compared to paint from suspects vehicle
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Process of comparison
- combination of select properties are chosen from each and reviewed
- the examiner draws a conclusion about the origins of the speciemans
- do they or do they not come from the same sourse?
- if one or more properties is different =not the same sourse
- based on education and training.
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physical evidence
individual characheristics properties of evidence that can be attributed to common sourse with an extremely high degree of certaninty
-
ridge characterists of fingerprints
striations on a bullet
wear patterns on footwear
DNA
break matches
example of physical evidence
-
class charactoristics
properties of evidence that can only be associated only with a group and not a single sourse
-
single layer automobile paint chip
foot wear/ tire without indiviual marks
Hair (without DNA potential)
Fibers
can only be good circumstanial evidence
examples of CLASS charactoristics
-
evidence
anything that tends to prove or disprove a fact of the case at trial
-
direct evidence
evidence that directly proves a fact without any inference or presumption
-
circumstantial evidence
- evidence gained from deductions made from related facts and circumstances indirect evidence
- Real, testimonal and relevant (probative)
-
its ability to corroborate events with data in a manner that is (as nearly as possible) free of human error and bias
The most important value of physical evidence
-
Automated Fingerprint identification (AFIS)
- computer database with finderprints
- converts scanned images of fingerprint into digital minute
- once a list is produced it is up to a trained examiner to match the print
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Combined DNA index system (CODIS)
- computer stores DNA profiles from around the country
- local state and national labs house profiles are interconnected
- all 50 states
- FBI houses national data and includes US army and puerto rico
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