Exam 1 Flashcards
ch 1-7
Forensic science is related to matters of _____?
Law
Forensic science _______ the scene, victim, suspect, and evidence.
Links
5 basic ingredients of a good processing methodology?
knowledge, skills and tools, methodical approach, flexibility, and coordinated effort.
Knowledge
not just a collector of things, seek information that will aid in understanding the scene
Skills and Tools
The technician must have the appropriate equipment and be skilled with it in order to collect the various types of evidence they may encounter
Methodical Approach
The methods employed by the technician must be all-encompassing and purposefully regular
Flexibility
Although methodical, the technician must also be flexible in order to deal with unique situations
Coordinated Effort
The entire team must coordinate their effort so everyone is pursuing the same goal.
Three crime scene integrity issues
addition, subtraction, movement
Addition Examples
shoe prints, fingerprints, fibers, hair, cigarette butts, soda cans, and coffee cups
Subtraction Examples
Trampled dust prints, bloodstains on victims clothing, trampled dew trails, loss of evidence on perimeter, loss of hair and fibers
Movement Examples
weapons moved, lights turned on, doors or windows opened/closed, staging by relatives
Five essential sketch elements
Heading, Diagram area, Legend, Title Block, Scale and Direction notation
Heading
a simple title that explains the purpose of the sketch
Diagram area
The actual sketch or drawing
Legend
Annotations that explains any symbols used in the sketch
Title Block
case number, address, date and time, and who drew it
Scale and Direction
Annotations that indicate the direction north as depicted by the sketch and whether any scale was used.
Class Characteristics
Limits to specific groups
Individual Characteristics
Limits to specific person
Three ridge patterns
Loop, whorl, Arch
Most common ridge pattern
Loop
Sources of DNA
Hair, blood, skin, ect
Can bloody clothing be placed in plastic?
Yes only when transporting to a dryer that is close by.
Two most common methods for collecting hairs and fibers
Tape and vacuum
Questions for initial responding officer?
Is it safe?
Considerations for placing the initial perimeter.
Primary focal points, secondary scenes, entry and exit points
Purpose of crime scene entry log.
Who, why, when did they enter.
Crime scene processing activities.
Assessing, observing, documenting, searching, collecting, analyzing
What is going back?
Going back is when new evidence is found you then go back and document from the start.
Four main search patterns?
line, grid, zone, spiral
Four elements of crime scene documentation?
Notes, photos, sketches, and reports
Three types of photographs.
Overall, evidence establishing (with landmarks), and close up.
Three problems in crime scene photography
confusion, identification, orientation
Photo log, what is it, how can it help?
Lists all photos taken and what is in the photo
First picture should always be?
Photo reference card
Crime scene hazards
chemicals, blood, weapons, structural stability
Always fill ______ when taking close ups?
the frame
Road mapping
a technique used to meticulously document bloodstain patterns at a crime scene by taking photographs with detailed labels and scale
Three variations of view with sketches?
Birds-eye view, extended, 3D
What is the basic goal of crime scene processing?
The goal of crime scene processing is to collect the evidence and the scene context with as much precision as possible.
Which two of the five police objectives are more closely related to crime scene investigation?
Crime repression and protection of personal liberty.
Why is physical evidence more objective than testimonial evidence?
Physical evidence is more objective because it is real and tangible.
What is the interpretive value of evidence a function of?
The interpretive value of the evidence is a function of time and the item’s surroundings.
What are the five ways in which context manifests itself in the crime scene?
- Predictable effects
- Unpredictable effects
- Transitory effects
- Relational detail
- Functional detail
What are the four questions that an investigator should ask about evidence?
- What is it?
- What function did it serve?
- What relationship does it have to any other items of evidence or to the scene itself?
- What does it tell us about timing and sequencing aspects?
Describe the forensic linkage triangle.
The forensic linkage triangle is the connection between the scene, subject, and victim using evidence gathered.
What are the five key ingredients required for a good crime scene examination?
- Knowledge
- Skills and tools
- A methodical approach
- Flexibility
- A coordinated effort
What are the three crime scene integrity issues that the CSI considers?
- Addition of materials
- Destruction of materials
- Movement of materials
What is the standard that the CSI uses when pursuing a solution to crime?
Beyond a reasonable doubt.
What is the difference between class and individual characteristics of evidence?
Class characteristics allow evidence to be compared to a group, while individual characteristics allow evidence to be compared to a specific person or object.
Which DNA analysis method is best for individualization in forensic work and why?
Short tandem repeat (STR) is the best for individualization because it combined with PCR creates better statistical discrimination than RFLP.
How is tape used to collect hair and fiber evidence at a crime scene?
Tape is used by sticking the adhesive side down multiple times and then sticking the tape to a non-porous backing.
Which fragments of glass are used to evaluate the direction of force?
Fragments containing the ridge lines on radical fractures are used for evaluation.
How is paint layering used to differentiate two paint samples?
The sequence and layering of paint samples are compared.
What is the most significant form of environmental variation in soil sample comparison?
The most significant form of environmental variation is the pollen located within the sample.
How does evaluating evidence from a pistol differ from that involving a revolver?
The revolver keeps the cartridge case within the gun, while pistols eject the cartridge into the scene.
What two components of a barrel does rifling refer to?
Rifling refers to the lands and grooves within the barrel.
How are bullets marked for evidence?
Ballistic evidence is individually containerized, labeled, and annotated to indicate where it was found at the scene.
Which method is better for collecting tool-mark evidence: collection of the entire item or casting of the mark?
The whole tool mark should be taken when possible, as important variations happen at a microscopic level which can be missed in casting.
What is the most significant class characteristic in shoe-mark examinations?
The tread design is the most important class characteristic as it can determine a brand or model.
What type of containers are used to collect fire scene evidence?
Unlined paint cans or glass jars are used to collect evidence at fire scenes.
What is the difference between forged writing and traced writing in forensic analysis?
Tracing lacks fluid movement and cannot be linked to a specific person, while forged writing can be linked to a specific person.
What is the most appropriate response by a crime scene technician for collecting a computer?
They should contact a supporting computer crime team before attempting to collect a computer for forensic analysis.
What are the two primary goals of concern to the initial responding officer at a critical incident?
The primary goals are bringing the site under control and coordinating resources.
Identify the five basic objectives the officer uses to achieve their goals.
- Document information provided
- Not become a casualty
- Provide emergency care
- Secure and control the scene
- Release the scene to appropriate authorities
How might failing to verify the address of a crime scene negatively impact the investigation?
It may cause investigators to get a warrant for the caller’s house rather than the actual crime scene.
What is the overriding rule for the responding officer regarding evidence preservation and emergency care?
Lifesaving care is a priority over evidence collection.
When is it appropriate to slow or stop EMS from entering a crime scene?
When it is obvious that the person is deceased, such as in cases of decapitation.
What should an officer be concerned with if tasked to accompany a victim to the hospital?
They should document any dying declarations or utterances made by the victim and collect any evidence removed from the victim.
What should an officer consider before chasing off numerous individuals at a crime scene?
Bring them under control and isolate them for identification and interviews.
What three things should be included within the initial responding officer’s crime scene barrier?
- Primary focal points
- Natural entry and exit points
- Secondary scenes
How might a natural or man-made barrier negatively affect the initial crime scene boundary?
It may exclude evidence past the barrier that could be relevant to the investigation.
What is the purpose of a crime scene entry log?
To record what time people entered and exited the crime scene and why they were at the scene.
What information should the initial responding officer provide to the crime scene team during the on-scene debriefing?
They should inform the team of everything they know, what they found, and what they did after arriving at the scene.
Why is sequence of order important in crime scene processing?
It is important because there is only one chance to process the scene in its original state.
What are the six basic processes accomplished during crime scene processing?
- Assessing
- Observing
- Documenting
- Searching
- Collecting
- Processing/analyzing
How might the step of documentation alter a crime scene?
Documentation such as road mapping blood stains has the ability to alter a scene.
Why must a crime scene technician be prepared to return to an earlier stage of the processing model?
It is important as new evidence can be revealed on later steps of the process.
Fill in the blank: The first recheck of the scene is a _______ check.
visual
Prior to placing a corpse in a body bag, what documentation efforts must the technician take?
- Photographs
- Sketching
- Feet and hands are bagged
- Physical examination
- Use of ALS
- Records of body position and condition
When are rechecks of the scene continued until?
They are continued until they return a negative result.
What happens during the first debriefing of a crime scene?
It happens at the crime scene upon the arrival of any new officers and CSI teams.
What is the significance of the phrase ‘in as pristine a condition as possible’ for crime scene technicians?
It helps prevent the unnecessary loss of evidence.
What is the primary concern of scene assessment by the crime scene technician?
The primary concern is the scope of the scene, scene integrity, contamination control, team approach, search methods, and the need of PPE.
Why is a single crime scene barrier considered ineffective?
It does not allow a buffer space for evidence and the crowd of onlookers.
How does enforcing the use of personal protective equipment (PPE) help control scene integrity?
It helps avoid contamination and deters people from entering the scene.
What are the two basic approaches to team composition in crime scene processing?
- Area approach
- Functional approach
Identify and describe one factor that affects decisions about team composition.
Single or multiple scenes affect team composition as it may favor an area approach.
What are the five basic patterns used to search a crime scene?
- Circle/spiral search
- Strip/line search
- Grid search
- Zone search
- Point-to-point search
What is a variation of the zone search and when is it used?
It is used in confined spaces where other search methods wouldn’t work.
Why is post-processing exposure to biohazards a problem?
It can cause the transmission of life-altering viruses.
How should a crime scene technician respond when presented with a possible drug lab?
They should leave the scene until a properly trained team can make it safe.
Why is it important to establish standard team processing techniques at a mass crime scene?
It prevents confusion between multiple groups collecting evidence.
What are the four key elements of crime scene documentation?
Photos/video, Sketches, Reports
These elements are essential for accurately documenting a crime scene.
Describe how a photograph might create an identification problem.
If there are no establishing shots then there is no way for the viewer to understand what they are looking at.
Establishing shots provide context to the viewer.
Describe how a photograph might create a confusion problem.
A confusion problem may be created in a photograph if there is no identification on evidence in the case of two shells being present how are they supposed to determine which piece of evidence is of focus.
Clear labeling of evidence is crucial to avoid confusion.
What are the three basic photographs associated with crime scene photography?
Overall photograph, Evidence establishing photographs, Evidence close-up/forensic quality photographs
These types of photographs serve different purposes in documenting a crime scene.
What is the purpose of an overall photograph?
Overall photographs depict the general conditions of the scene and the layout of the scene.
They show where landmarks are and the scene before any alterations.
What is the purpose of an evidence establishing/relationship photograph?
This shows where evidence is located at a scene in relation to other items and landmarks.
It helps in understanding the context of the evidence.
How does the f-stop affect the resulting photograph?
The f-stop controls how much light is let into a shot by determining how wide the lens opens.
A higher f-stop means less light, while a lower f-stop means more light.
How can a crime scene technician prevent overexposure or bleaching out of close-up photographs when using fill-flash techniques?
The use of off-set flash, oblique lighting, or a ring light will correct the bleaching or overexposure of a shot.
These techniques help manage lighting effectively.
Describe at least three critical mistakes that occur when using video cameras in the crime scene.
- Not letting the camera focus.
- Having improper lighting.
- Recording with audio on.
Each mistake can compromise the quality of the recorded evidence.
What is the primary purpose of the crime scene sketch?
The primary purpose of the crime scene sketch is to show the layout, orientation, and interrelationships of the scene and the evidence.
What are the five essential elements of the crime scene sketch?
Heading
Diagram area
Legend
Title block
Scale and direction
What are two variations in creating a sketch that will effectively allow the crime scene technician to document evidence on vertical objects?
Cross-projection is when it uses the traditional birds eye view but then laying down walls to depict evidence on vertical objects.
Elevation sketch shows a side view of a portion of the scene such as a interior wall or vertical structure.
In rectangular coordinates, how are fixing measurements made to surrounding walls?
It is done by measuring the right angles from the evidence to the surrounding walls and surfaces.
Give a simple example and describe fixing a regularly shaped object with triangulation.
Triangulation of a cartridge casing is done by taking two measurements from a distinct landmark to two points on the casing and then taking two measurements from a different distinct landmark to two points on the casing.
In what circumstance is baseline mapping most effective?
Baseline mapping is most effective is exterior scenes lacking evident landmarks.
In what situation are rectangular coordinates on a grid particularly effective?
Rectangular coordinates on a grid are effective in large-scale scenes where there are no evident landmarks and multiple teams working such as gravesites.
In what situation would triangulation on a baseline be effective?
Triangulation on a baseline is effective on exterior scenes where evidence is not to widely scattered but no evident landmarks.
What is the current most significant limitation when using total stations or 3-D automated laser scan systems?
The technology is not advanced enough to handle all types of scenes and standard scene documentation procedures.
Why is it unnecessary to orient a total station to true north?
The instrument cannot be aligned using a magnetic compass so it is more accurate to align by an angle.
