CSI Weeks 1-3

Exam 1 info

Evidence

anything that is legally submitted to a competent trier of fact as a means of ascertaining the truth of any alleged matter under investigation.

Trier of Fact

The Judge in the case of a bench trial or The Jury in the case of a jury trial

Testimonial Evidence

Given in the form of statements made under oath, usually in response to questioning.

Real Evidence

Evidence that has objective existence. In other words, this type of evidence has size, shape, and dimension. Also known as physical evidence.

Direct Evidence

Type of evidence supports a conclusion of fact without inference.

Circumstantial Evidence

Type of evidence requires inference to connect it to a conclusion of fact.

Associative Evidence

Evidence that can be attributed to, or associated with, a specific person, place, or thing, thus establishing inferred connectivity.

Trace evidence

Any evidence that is small in size (hairs, fibers, paint, glass, soil), which would require microscopic analysis to identify it.

Transfer Evidence

A type of evidence that is passed from one item to another, typically as a result of contact or action. Careful analysis of this evidence can associate the questioned evidence with a known source.

Transient Evidence

Physical evidence present at the crime scene that is either fragile or at great risk for loss, alteration, or destruction if not properly identified, documented, collected and preserved as soon as possible.

Classification

occurs when an item of evidence is assigned to a specific class where it belongs.

Class characteristics

the item is placed into a group (aka class) with other items having the same chemical and/or physical properties.

Individualization

occurs when an item of evidence is assigned to a class containing only one member (i.e, itself).

Individual characteristics

The item of evidence is individualized or identified because it has unique properties.

Court Orders (Search Warrants)

may be required to search a crime scene and/or for the collection  of evidence, such as blood samples, hair specimen, teeth impressions, etc. from a suspect.

Exigent Circumstance

an emergency situation in which there is not adequate time to get a search warrant before the evidence could be destroyed or life could be endangered.

Fruit of the Poisonous Tree

states that any information derived from a piece of illegally obtained evidence is inadmissible in court.

Chain of Custody (Chain of Evidence)

shows who had contact with the evidence, at what time, and under what circumstances. In addition, it provides information regarding what changes, if any, were made to the evidence.

Known Samples

are samples from an identified or known source that are provided to the crime laboratory for comparison to unknown (i.e., questioned) samples.

Questioned Samples

are samples collected at the crime scene from an unknown or unidentified source and are submitted to the laboratory for testing and identification.

Elimination Samples

are those which are taken from individuals who have had legitimate access to a crime scene that will be used as a comparison with evidence collected from the scene. Are used to exclude the individuals who have a legitimate reason to have been at the crime scene.

Blank Samples

are those which do not contain evidence, but are collected, packaged and preserved at the crime scene using the same method as was used to collect the questioned sample.

Physical Evidence can?

1. prove a crime has been committed or establish key elements of a crime,

2. place the suspect in contact with the victim or with the crime scene,

3. establish the identity of persons associated with the crime,

4. exonerate the innocent,

5. corroborate the victim's testimony.

Negative Evidence

 may provide useful information and even stop defense arguments at the time of trial. Evidence that disproves a theory. 

Five goals of Incident Management

1. Document the provided information

2. Not becoming a casualty

3. Provide for emergency care

4. Secure and control the scene and all those within it

5. Release the scene to the appropriate authorities (The detective or CSI)

Primary Focal Points

Areas that stand out within a scene

Natural Entry and Exit Points

Can help determine where perpetrators enter and exit a scene

Debriefing Purposes

1. Scope of the scene

2. Scene integrity and contamination control

3. Team approach and composition

4. Search methods to be used

5. Personal protective measures

Inner Area

Restricted to personnel actively involved in scene processing

Middle Area

A working zone that serves as a staging area for equipment such as cameras, bulky gear, or investigative kits. It may also be used for trash collection and temporary evidence storage

Outer Area

Typically where onlookers, media, and non-essential personnel are kept.

Assessing

Before taking any action, the CSI must assess the circumstances to determine an appropriate course of action

1. Assessment is an ongoing process. The CSI must continuously evaluate the situation and adjust the processing plan as necessary

Observing

The CSI visually inspects and mentally registers the condition of the scene and any artifacts present

1. Although observation may seem nonintrusive, it is often conducted in conjunction with movement and other search efforts, which can have an impact on the scene.

Documenting

includes a variety of methods such as written notes of observations, photography, video recording, and sketch creation

1. This step is critical for preserving the original state of the scene before any items are moved or altered.

Searching

This step is always intrusive, as it involves moving items to examine surfaces that are not visible

1. Because of its impact on the scene, any physical search should occur only after thorough documentation has been completed.

Collecting

1. The physical removal of items from the scene is inherently intrusive.

   Some collection methods are more disruptive than others (e.g., collecting a firearm vs. recovering a projectile embedded in a wall).

Processing/Analyzing

This involves applying methods such as fingerprint powder, chemical enhancements, or other forensic techniques.

1. These actions are significantly intrusive as they alter the item's original condition and can even change the scene itself.

Circle/Spiral Search

 an effective method commonly used for interior scenes. In this approach, the searcher begins on the outer edge of the area or room and moves inward in a slow, controlled spiral pattern. Alternatively, the search can be conducted in reverse, starting from the center and spiraling outward. The key consideration in this method is maintaining a consistent and deliberate pace to ensure thorough coverage and minimize the risk of overlooking evidence.

Strip Search

most commonly used in exterior scenes when evaluating large areas. The searcher begins at one end of a designated strip and proceeds in a straight line to the opposite end. Upon reaching the end, the searcher moves to the next adjacent strip and continues the process in the reverse direction. This back-and-forth pattern ensures systematic coverage of the entire area and is particularly effective for open fields, parks, or large outdoor crime scenes.

Line Search

 A variation of the strip search, distinguished primarily by the number of searchers involved. In a line search, a group of searchers forms a line across the search area, each responsible for a specific lane. The team moves together in a single direction, systematically scanning their assigned lanes. This method is especially useful for large outdoor scenes with uneven terrain. The most critical consideration is that the team moves as a cohesive unit, maintaining the pace set by the slowest searcher to ensure thorough coverage.

Grid Search

A variation of the strip search in which the area is divided into two sets of strips or lanes that intersect at 90-degree angles. The searcher conducts a standard strip search along one set of lanes, moving up and down each lane from one side of the area to the other. After completing this, the searcher performs a second search along the perpendicular set of lanes, creating a thorough double coverage of the entire area. This method provides a more detailed examination by allowing a single searcher to review the ground twice from different directions.

Zone Search

Small, Confined Spaces: This approach is ideal for areas that are difficult to search using patterned movements, such as the interior of a vehicle. The space is divided into manageable zones, and each zone is searched thoroughly before moving on to the next.

Large Exterior Scenes: The area is divided into physical grids or zones. This method is particularly useful for extensive outdoor scenes with scattered evidence, remains, or debris—such as those found in airplane crashes.

Point to Point Search

This method is rarely practiced in the United States but is taught at the Metropolitan Police Academy in Hendon, England. In this approach, the CSI identifies the primary focal points and determines the order in which to process them. The investigator fully processes the first focal point and its surrounding area before moving on to the next. Without proper training and experience, this method can become disorganized and appear haphazard.

Rectangular Coordinates

Best suited for crime scenes with clear, specific boundaries, such as interior walls. The CSI "fixes" evidence by measuring right angles from the evidence to the surrounding walls. Typically, two measurements to the center of mass of the item are taken, which is less precise than triangulation. For regularly shaped items like furniture, two measurements from two different points can also be taken.

Triangulation

 The most effective method for fixing evidence. The CSI uses a minimum of four measurements from two distinct landmarks in the room to two points on the item to accurately map regularly shaped objects. For irregularly shaped items (e.g., a pile of clothing), two measurements to the center of mass are sufficient.

Baseline Coordinates

Best suited for exterior scenes without obvious landmarks. The baseline method begins with a datum point, which is established by triangulating to nearby landmarks. A tape measure is extended along a cardinal direction from this point, and the distance from each item to the baseline is measured at right angles. The CSI also records the position along the baseline where the evidence measurement intersects.

Polar Coordinates

An older technique used for mapping large, open exterior scenes where evidence is scattered, such as airplane crashes or bombing scenes. Using a sighting device, the CSI takes 2-3 measurements from a known point to the evidence: horizontal distance, horizontal angle, and elevation difference.

Triangulation or Rectangular Coordinates on a Grid

Effective for large-scale scenes with multiple teams actively mapping areas lacking significant landmarks. The grid itself serves as a reference, allowing teams to use triangulation or rectangular coordinate methods within each grid section.

Triangulation on a Baseline

Useful in exterior scenes where evidence is not widely scattered, but landmarks are insufficient. The baseline is established by triangulating both ends to surrounding landmarks, with reference points marked every 5-10 feet. Evidence locations are then mapped by triangulating from these reference points.

Tool Stations

are automated surveying systems that utilize methods similar to polar coordinates. A total station combines transits, lasers, and computer technology to capture precise measurements from the scene. The data can then be downloaded into computer-aided drafting (CAD) software to create scaled, detailed drawings. Total stations became popular in forensic investigations, particularly for documenting traffic accidents—capturing debris, vehicles, skid marks, and more. However, a key limitation is the need for a clear line of sight between the total station and the evidence.

FARO 3D Scanners

represent an evolution of total station technology, automating the process further. These scanners emit a laser beam from a rotating mirror that sweeps across the scene. The laser reflects off objects back to the scanner, which calculates distance by measuring the phase difference between the emitted and returning laser light. In addition, FARO scanners have internal cameras that capture photographic image data to complement the laser measurements.

OSCR360

is a versatile system featuring a 360-degree spherical capture kit. OSCR360 photographs the entire environment in a spherical format, providing views from the center of the image in virtually every direction. Its software enables the creation of a virtual walkthrough of the crime scene, offering an immersive experience for investigators and jurors alike.

Heading

 A notation that explains the purpose of the sketch-why it was created.

Diagram Area

The actual drawing of the scene, showing the layout and evidence

Legend

A key that explains the symbols, labels, or markings used in the diagram.

Title Block

Contains relevant information such as the location of the scene, the date, and the name of the sketch creator.

Scale

Indicates whether a scale is used and specifies the scale ratio (e.g., 1 inch = 5 feet).

Direction

Shows the orientation of the sketch relative to compass directions

Cross-Projection or Exploded Sketch

Combines the bird's-eye view of horizontal surfaces with the walls "laid down" flat to show evidence present on vertical surfaces

Elevation Sketch

 Provides a side view of a specific portion of the scene, such as an interior wall or other vertical structure. This is used to map and document evidence found on walls or similar surfaces.

Three-Dimensional Sketch

Offers a more realistic perspective by presenting the scene in 3D, helping to visualize spatial relationships more accurately

Digital Single Lens Reflex (DSLR)

1. Uses a mirror and optical viewfinder

2. View through the lens with your eye

3. Can use interchangeable lenses

4. Categorized as “big, bulky, and hefty”

Mirrorless

1. Smaller size and less weight when compared to the DSLR

2. Direct to sensor viewing

1. Everything that you view in the camera is all coming directly through the digital system

2. Live exposure

1. There is no mirror, so what you see through the viewfinder is not part of an optical system

2. The live exposure leads to simplified mechanism and shutter systems

1. There are electronic shutters where nothing is physically going over the sensor; it shuts off electronically

2. Better frames per second

1. Better for aerial or sports/action photography

2. Lots of photos in a single second (faster)

3. Resolution

1. If the sensor is the same size, it produces similar resolution quality to DSLR cameras

2. Overall better resolution since you are most likely updating to a newer camera (does not necessarily have to do with the camera type)

Relevant

Evidence having the tendency to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would without the evidence.

Material

Evidence that is impactful to the case; offered to prove or disprove a fact in issue

Fair and Accurate Representation

Also referred to as authenticity, meaning the photographs represent the scene as it was on the date of the incident accurately.

Fill the Frame

Refers to eliminating irrelevant subject matter in the photograph composition

1. Can be accomplished by

1. Getting closer to the primary subject (left image)

2. Orienting your camera correctly (middle image)

3. Raising or lowering your camera to get rid of the foreground or background respectively (right image)

Maximize the Depth of Field

Everything in the photograph should be in focus

International Organization for Standardization (ISO)

The Camera’s sensitivity to light Less sensitive sensors that require more light have lower numbers

1. Example: ISO 100 is used when there is ample scene lighting

2. The higher the ISO, the more “noise” in the photo

3. Forensic use

1. Exam-Quality photos: 100

2. Outside photographs (bright, sunny day): 100

3. Everyday photographs (morning, evening, indoors): 400

4. Painting with light or nighttime: 800

F-Stop

A lens setting that indicates the size of the aperture.

1. Controls the depth of field (what is in focus) and how much light is let in

1. Higher f-stops ⟶ Smaller aperture, less light, larger depth of field

• Example: f/22

1. Smaller f-stop ⟶ Larger aperture, more light, smaller depth of field

• Example: f/4

1. Forensic Use

1. Everyday photographs: f/8-f/11

2. Exam-Quality photographs: f/11-f/22

3. Nighttime photographs: f/4-f/5.6

• Theoretically this is correct, however when you get this low you lose a lot of depth of field

• A better solution would be to increase the ISO or shutter

1. The f-stop is directly related to the aperture of the diaphragm opening of the lens

1. Diaphragm: Set of blades forming a circular opening, which can be opened or closed to let more light in or restrict the light entering the camera, respectively

2. Aperture: Size of the resulting diaphragm opening

3. F-stop: Fraction relating the size of the aperture opening to the lens focal length being used

4. The f-stop, focal length of the lens (FFL), and diameter of the diaphragm (DOD) are mathematically related as follows:

(FFL/f-stop) = DOD

Shutter Speed

The length of time the camera's shutter remains openThe faster the shutter, the less light that enters the camera

1. The slower the shutter, the more blur that can occur

2. Represented as a fraction on the camera

3. There is more flexibility with what the shutter is set to, especially if you have a tripod

4. Can freeze motion

5. 1/125th will “freeze” a walker, enabling the face to be recognized

6. 1/250th will “freeze” a jogger, or someone running, or jumping

7. 1/500th will “freeze” a bicyclist or a slow-moving vehicle (up to about 30 mph)

8. 1/1000th will “freeze” a vehicle going up to 60 mph

9. 1/2000th will “freeze” an airplane powered by propellers

10. Can eliminate rain/snow

11. Slower shutters: 1/15 or slower

12. Forensic use

13. The slowest you should while holding the camera is 1/60 for a standard 50mm lens

14. Aerial photography: 1/500 or 1/1000

15. Painting with light/Bluestar/laser photography: Bulb

Auto (green box)

The camera decides the settings

Program (P)

The photographer sets the ISO, the camera sets the shutter and f-stop

Shutter Priority (Tv)

The photographer sets the shutter, the camera sets the ISO and f-stop

Aperture Priority (Av)

The photographer sets the f-stop, the camera sets the ISO and shutter

Manual (M)

The photographer sets all the settings

The Theory of Reciprocity

 states that a variety of f/stop, ISO, and shutter speed combinations result in the same exposure. The exposure triangle can be used to assist with determining the correct combinations. The changes must equal 0.

UV/Haze/1A/Skylight Filters

1. Lens protection from dropping the camera or other physical damage

2. Filtering out excessive blue from the sky.

Polarizer Filters

Can eliminate reflection (water or windows), enrich color saturation, and make skid marks more obvious on scene

Colored Barrier Filters

Used in conjunction with an alternate light source (ALS)

1. While the CSI might use goggles to see fluorescence with an ALS, the camera needs a barrier filter the same color as the CSI’s goggles in order to photograph the fluorescence

2. Also needed when photographing dye stain latent fingerprints

Wrattan 87 Filter

An IR filter used to block all visible light while transmitting IR light

Normal Lens

is typically 50mm. These lenses show the true distance between the photographer and the items being photographed.

Close Up lens

 it is best to use a 100–120mm lens. Using a standard lens can exaggerate the distance between facial features, causing the face to appear "stretched." The nose may look more prominent, while the ears may appear smaller.

Wide angle lenses

Lenses with a focal length shorter than 50mm. These typically range from 35mm down to fisheye lenses. Offer a broader field of view, increased depth of field, and elongation of distances from foreground to background.

Telephoto Lenses

Lenses with a focal length longer than 50mm. Ranging from 60mm to 1200mm. magnify distant objects, have a narrower field of view, compress distances from foreground to background, and offer a shallower depth of field.

Macro Lenses

are designed to magnify small objects so they fill the frame of the photograph, making them ideal for comparison photography (e.g., latent print or toolmark photography). Typically offer 1:1 or 1:2 magnification and produce the clearest close-up images when compared to other magnification alternatives, such as extension tubes or close-up filters.

Aberrations

Defects in an image produced by a lens, account for a reduction in the resolution of an image

Diffractions

The bending of light when it strikes an edge, causes a loss of resolution, a loss of edge sharpness, and a loss of clarity in the image

Barrel Distortion

An effect of using a wide-angle lens that results in straight lines appearing at the edges of an image to appear bent outward. Wide angle lenses elongate the scene which make near and far elements appear further apart

Pincushion Distortion

An effect of using a telephoto lens that results in straight lines appearing at the edges of an image to appear bent inward. Telephoto lenses compress the scene which make the near and far elements appear closer together.

Examination or Comparison quality photographs

A specialized form of close-up photography. These are photographs that are used for comparisons, including fingerprints and shoe/tire impressions.

Bluestar

a chemical reagent used to detect hidden traces of blood, even at dilutions as extreme as 1:100,000. It produces a chemiluminescent reaction that is stronger and lasts longer than that of conventional luminol, and it does not require complete darkness for effective photography.

Laser photography

a valuable technique for illustrating bullet trajectory pathways.

UV Light Photography

useful for screening biological fluids, fibers, and for photographing fingerprints processed with dye stains. Reflective UV photography can also be used to document deep muscle bruising. When photographing fingerprints, comparison-quality settings must be used.

Aerial Photography

involves capturing images from an aircraft in flight. This can be done using manned aircraft, such as helicopters, or unmanned aerial vehicles (drones).provide an overview that complements ground-level images, offering a broader spatial perspective of the scene and its surroundings. This perspective can be especially useful for documenting elements such as a suspect’s potential flight path or details of an officer-involved shooting—like obstructions present or the officer’s line of sightWhen conducting aerial photography, the ideal time is between 10 a.m. and 2 p.m. on a bright, overcast day to minimize shadows. It is best to prioritize shutter speed, setting it between 1/500 and 1/1000 seconds. Additionally, try to keep the ISO as low as possible to reduce noise and maintain image quality.

Painting with Light

a technique used when a single flash is insufficient to illuminate a large, dimly lit scene. The camera is placed on a tripod with the shutter open while a person moves around the scene, firing a handheld flash multiple times to "paint" the light.

Order of Evidence Collection

1. Transient evidence (fragile or easily lost) should be collected and preserved as soon as possible.

2. Biological evidence should be collected next, before any latent print processing.

3. Latent print processing is done last because many physical or chemical methods could contaminate biological evidence.

Manila Envelopes and Paper bags

Commonly used for general evidence.

Packaged in paper materials

Biological evidence

Boxes

Various sizes are used for large or oddly shaped items