1. Crime Scene Procedures, Techniques and Analysis

2. What is the difference between processing and analysis?
Processing follows a series of standards steps
Analysis depends on: detailed observation, proper processing, making logical connections, laboratory analysis, analysis of scene patterns, and integrating all the data available
Crime scene analysis follows the steps of the Scientific method

3. Types of Scenes
Two major categories of criminal activities having crime scenes:
property crimes (larceny, burglary, auto theft)
crimes against persons (assault, battery, sexual assault, robbery, murder)
The nature of the scene will affect the way it is handled:
indoor or outdoor
public or private property

4. Types of Scenes (contd.)
There is also a differentiation between where the crime happened and where other evidence or a body may be found.
Where the crime occurred is called the primary crime scene
Where any other evidence is found after the commission of the crime is called a secondary scene
A dumpsite is a special kind of secondary scene which refers to where a body is found when the crime did not happen in that location.

5. First Responders
A first responder is the first police officer or investigator to arrive at and witness a crime scene. The first responders are often a uniformed patrol officer.
The first responders have a legal obligation to take care of the scene until the crime scene unit, medical examiner, prosecutors, and investigators arrive.

6. ADAPT
The mnemonic guide used to outline the duties for a first responder.
A= Assess the crime scene and assist the injured
D= Detain the witness(es)
A= Arrest the perpetrator
P= Protect the crime scene
T= Take notes

7. Scene Survey & Evidence Recognition Scene Searches Documentation
Steps in Processing
Scene Survey & Evidence Recognition
Scene Searches
Documentation
Evidence Collection & Preservation
Release of the Scene

8. 1. Scene Survey & Evidence Recognition
A scene survey is an initial walk-through to establish the type of scene, note any transient evidence, and recognize any potential physical evidence
Transient evidence is evidence that is easily destroyed or compromised
Evidence recognition is the determination of which physical evidence is relevant to the case as opposed to being part of the background

9. 1. Scene Survey & Evidence Recognition (contd.)
The crime scene investigator should use a scientific approach when conducting the scene survey and develop a working hypothesis

10. 2. Scene Searches
The objective is to note every condition and every relevant item of physical evidence
The method chosen depends on the type of scene, location, and the area it covers
Methods: zone or quadrant; grid or strip; contracting or expanding spiral; double grid; and the “link” search method
“Link” search method refers to making logical connections based on the working hypothesis

11. Scene Search Methods

12. Scene Search Methods
A) Zone or quadrant- This method is ideal for indoor or vehicle searches.
In a zone search, the CSI in charge divides the crime scene into sectors, and each team member takes one sector. Team members may then switch sectors and search again to ensure complete coverage.

13. Scene Search Methods
B.) Spirals- Spiral patterns are a good method to use when there is only one CSI at the scene.
For outward start at the center of the scene and work your way out.
For inward start from the perimeter and work toward the center.

14. Scene Search Methods
C.) Grid-A grid search is simply two parallel searches, offset by 90 degrees, performed one after the other
Strip- Commonly used when searching a large area looking for a large object. CSIs will stand in one long line and all walk the same direction.

15. 3. Documentation
The creation of a detailed, complete record of the scene using:
Notes
Sketches
Photographs
video recording
Each method requires the date, time, location, case number, and name(s) of the person(s) recording or collecting evidence
With evidence items the following additional information is required:
Description- must describe in detail but not make any assumptions
the number assigned

16. 3. Documentation (contd.)
A. Sketches:
Are drawings of scenes with measurements or to scale, depicting the correct spatial relationships between scene fixed points and evidence items
Two general types: preliminary and finished
A cross-projection sketch is used to show the three dimensional characteristics of the scene
Every sketch should have a compass, scale, legend, key, title, and measurements.

17. Scene Sketches

18. Scene Sketches (contd.)

19. Scene Sketches (contd.)
The exact location of objects can be obtained by the triangulation using two fixed points

20. 3. Documentation (contd.)
B. Notes:
Written or audiotaped records for documenting a crime scene
Contains information such as the initial condition of the scene, names and contact information for witnesses, vehicle license plate numbers, etc.
Also includes photo logs, evidence logs, and security logs
Notes are often used as the basis for preparing a formal written report at a later time

21. Documentation (contd.)
C. Photographs:
Objective is to completely document the scene
Both technical and forensic aspects to consider
Technical Aspects:
Camera types: “point & shoot”, 35 mm, 4x5, digital
Lighting (front, back and side lighting)
Sharpness (focus & lack of camera motion)
Exposure (f-stop and exposure time)

22. Photographs Forensic aspects: Proper selection of subjects and objects
Overall, midrange, and close-up photos

23. Photographs (contd.) Forensic Aspects Evidence photos:
In their original location
With & without markers in place- to match with all documentation
With & without a scale in place- to show the dimensional information and the proportion of measurements

24. Documentation (contd.)
D. Video Recording:
Videography has several potential roles:
As a stationary monitor, recording all individuals who entered the scene and all activities
To document the overall layout of a scene, evidence location, pattern evidence
Narration is optional and may be used to help understand and orient the viewer

25. 4. Evidence Collection and Preservation
After documentation, all physical evidence items recognized as relevant are collected, packaged, and preserved
Collection Methods:
Whenever possible, items should be collected “intact,” otherwise a sampling method is used
Sampling methods include using forceps, tape lifts, or vacuuming the item
Vacuuming is a method of last resort because it picks up too much other material
Biological material may be sampled by cutting, swabbing or scraping
Shaking or scraping the item should be done in a lab environment

26. 4. Evidence Collection and Preservation
Numbering & Description Methods:
Numbering and a brief description are marked on the packaging and in the evidence log
Description should be as specific as possible without making assumptions
Ex.- One size large blue shirt with red/brown stain
Numbers used at the scene, on the packaging, and in the evidence log should all agree

27. 4. Evidence Collection and Preservation
Packaging Options:
The majority of items will be packaged in paper containers or bags
Small items and particles should be packaged in a druggist fold as the primary container, and then a secondary container to prevent any loss
Plastic zip-lock bags are suitable for solid items that are non- biological

28. 4. Evidence Collection and Preservation
Special containers are required for fire debris, liquid samples, weapons, and sharp objects
Packages are sealed at the scene using tamperproof evidence tape

29. 4. Evidence Collection and Preservation
Control & Comparison Standards:
Required to ensure that a lab test is working properly or to permit a proper comparison
Four major types:
A known sample (exemplar or reference) is one whose origin is known with certainty
An alibi known sample is a known specimen from an alternative source
A blank control is a specimen known to be free of the item or substance being tested
A substratum comparison sample is the underlying material or surface on which the evidence is found or has been deposited

30. 4. Evidence Collection and Preservation (contd.)
Laboratory Submission:
A specific “Request for Analysis” form is completed for evidence items submitted for forensic lab analysis
The form should have the following information:
Type of incident
Date and time of incident
A brief description of the case facts
Names of victim(s) and suspect(s)
A list of items being submitted
Types of analyses or tests required
Submitting agency & investigator contact information

31. 5. Crime Scene Analysis and Reconstructions
Crime scene analysis involves theory building from all scene and investigative information
Investigative information includes:
Forensic laboratory analysis and comparisons of all relevant evidence submitted for analysis
Medical examiner’s report on the cause and manner of death, which usually includes the results of toxicological analysis of biological samples from the autopsy

32. 5. Crime Scene Analysis and Reconstructions
The formulation of the “best theory” of the events in a case
Based on all the available evidence (such as autopsy reports and lab reports), information, and supportive data
May require experiments to try and duplicate some of the events (e.g. bloodspatter)
May be complete, partial, or limited
Reenactment:
A hypothetical rendition of a set of events at a crime scene based on the reconstruction.

33. Digital Evidence and Forensic Computer Science
Digital evidence includes any device which records or retains digital records (e.g. computers, phone answering devices, cell phone logs, pagers etc.)
Investigative areas:
Extracting readily decipherable information from recording devices
Extracting password protected or “deleted” information from recording devices
Pursuing perpetrators of internet-based crimes