1. Forensic Science: Fundamentals and Investigation
The Crime Scene
Forensic Science: Fundamentals and Investigation
Bertino

2. The Seven S’s of Crime Scene Investigation
Secure the scene
Separate the witnesses
Scan the scene
Seeing the scene
Sketch the scene
Search for evidence
Secure the collected evidence
Forensic Science: Fundamentals & Investigations, Chapter 2

3. First Responding officer
First on scene is responsible for:
Acquiring medical assistance for injured
Detaining any suspects and witness
Secure the scene to greatest extent possible
Look for points of entry and exit
Call for any needed personnel
backup or forensic investigator
Need to access injured from indirect route as to not disturb the evidence.
Need to interview anyone present that may have knowledge of crime.
Who is needed on scene is dependent on nature of crime.
Once the scene is secure the lead investigator will take over for first responding officer
Forensic Science: Fundamentals & Investigations, Chapter 2

4. Securing the scene A perimeter needs to be set
Preserves and protects scene and evidence
May be necessary to set up multi level perimeters
Investigators should never do anything that might alter the crime scene including smoking, eating, drinking, or littering.
Lead investigator determines boundaries of scene (must contain crime, all exit and entry points, and all areas of evidence)
Begins documentation of evidence and scene
Everything needs to be documented before it is touched.
Forensic Science: Fundamentals & Investigations, Chapter 2

5. Multi Level Containment
1st level: contains crime, all areas with evidence plus buffer zone, and all entry exit points
2nd level: provides area for buffer zone, officers, command center, equipment, crime log is kept in this area (NO evidence)
3rd level: perimeter containment keeps foot traffic and unauthorized equipment out.
1 level of containment can result in contamination of scene because everyone and everything is there.
Detailed log of who and what enters the scene must be maintained.
Forensic Science: Fundamentals & Investigations, Chapter 2

6. The Crime Scene Investigation Team
Who is at the crime scene?
Police and
District attorney (possibly)
Crime scene investigators
Medical examiners
Detectives
Specialists
Forensic Science: Fundamentals & Investigations, Chapter 2

7. Searching the Scene
The search for physical evidence at a crime scene must be thorough and systematic.
The search pattern selected will normally depend on the size and locale of the scene and the number of collectors participating in the search.
Before search begins area should be surveyed
The Walkthrough—initial survey of the crime scene
Perpetrator’s point of entry and exit are located.
Indirect path is taken to the center of the crime scene.
Obvious items of evidence are located and documented.
The conditions of the scene are observed and recorded.
Special attention is paid to item or conditions that suggest timing of the incident or do not appear to belong.
Forensic Science: Fundamentals & Investigations, Chapter 2

8. Crime-Scene Search Patterns
Pattern used depends on nature of crime
Crime needs to be reconstructed based to aid investigation
Line/Strip Search Pattern
One or two investigators start at the boundary of the crime scene and search in straight lines across to the other side of the crime scene.
Grid Search Pattern
Two or more investigators form a grid by searching in line patterns that overlap and are perpendicular to each other.
Spiral Search Pattern
One investigators searches in a spiral path from the center of the crime scene to the boundary (outward) or from the boundary of the crime scene to the center (inward).
Wheel/Ray Search Pattern
Several investigators search in straight lines from the center to the boundary (outward) or from the boundary to the center (inward).
Quadrant/Zone Search Pattern
The crime scene is divided into smaller sections (zones). One or more investigators are assigned to search each zone.
Forensic Science: Fundamentals & Investigations, Chapter 2

9. Searching the crime scene
Vehicle Searches
Investigators search interior and exterior of vehicle.
The vehicle may be searched at the crime scene or at the police department or crime laboratory garage
Forensic Science: Fundamentals & Investigations, Chapter 2

10. Recording the Crime Scene
Photography, sketches, and notes are the three methods for crime-scene recording.
Ideally all three should be employed; however, as is often the case, personnel and monetary limitations may prohibit the utilization of photography at every crime site.
Note taking begins when the investigator is contacted and requested to report to the crime scene
Forensic Science: Fundamentals & Investigations, Chapter 2

11. Crime Scene Notes The crime scene notes should begin with:
The identity of person who contacted the investigator
Time of contact and arrival at the crime scene
Preliminary case information
Personnel present on arrival and those being contacted
Forensic Science: Fundamentals & Investigations, Chapter 2

12. Crime Notes…
Notes contain a personnel log, all observations made by the investigator, and the time observations were made.
Notes are taken in a uniform layout, concurrently as the observations are made.
Notes are written in a bound notebook in blue or black ink
Forensic Science: Fundamentals & Investigations, Chapter 2

13. Crime Scene Photography
Crime scene photographs should record the area in which the crime actually took place and all adjacent areas where important acts occurred.
The most important prerequisite for photographing a crime scene is for it to be in unaltered condition
Each crime scene should be photographed as completely as possible in a logical succession. The sequence will show the overall scene first, then work down to individual pieces of evidence that jurors in the trial can easily relate back to the larger scene
Forensic Science: Fundamentals & Investigations, Chapter 2

14. Crime Scene Photography
Required Photographs
Overview photo
Medium range photo
Close-up photo
Close-up photo with scale
Overview photographs of the entire scene and surrounding area, including points of exit and entry, are taken first.
Taken from the outside borders of the scene and from various angles
If the crime scene includes a body, photographs must show the body’s position and location relative to the entire scene.
Include a “visual tag,” an object recorded in multiple overview photographs, to help visually piece the scene together
Medium-range photographs show the layout of smaller significant areas of the crime scene.
Taken with evidence markers in place to show the spatial relationships between and among pieces of evidence in greater detail than the overview photographs.
Include at least one photograph of the “center” of the scene.
In violent crimes, this usually includes the site where the victim was found and the surrounding area.
Close-up photographs are taken last and show greater detail of individual objects or evidence.
Taken at a 90° angle to the object, with and without evidence markers and scales.
Scales should be placed as close to the evidence as possible without affecting it in any way.
After the 90° photographs have been taken, photographs from other angles may be taken.
The most important close-up photographs are those depicting injuries and weapons lying near a body.
After the body is removed from the scene, the surface beneath the body should be photographed.
Forensic Science: Fundamentals & Investigations, Chapter 2

15. Forensic Science: Fundamentals & Investigations, Chapter 2

16. This sequence of crime-scene photographs shows the proper progression of photographing the scene. The sequence begins with an overview photograph of the entry to the victim’s bedroom showing evidence markers in place.
Forensic Science: Fundamentals & Investigations, Chapter 2

17. This sequence of crime-scene photographs shows the proper progression of photographing the scene. The medium-range photograph shows the evidence marker next to the door denoting a cartridge case. Richard Saferstein, Ph.D.
Forensic Science: Fundamentals & Investigations, Chapter 2

18. This sequence of crime-scene photographs shows the proper progression of photographing the scene. The close-up photograph shows the cartridge in detail with a scale in the photograph. Richard Saferstein, Ph.D.
Forensic Science: Fundamentals & Investigations, Chapter 2

19. Crime Scene Sketch Clearly show the layout of a crime scene
Illustrate the relationship in space of all significant items and features
Clarify objects and features already described in notes or shown in photographs
Show measurements over long distances and topography of outdoor scenes
Depict possible paths of entry, exit, and movement through the scene
Forensic Science: Fundamentals & Investigations, Chapter 2

20. Rough Sketch
A rough sketch is created at the crime scene and contains an accurate depiction of the dimensions of the scene and shows the location of all pertinent objects and features.
Forensic Science: Fundamentals & Investigations, Chapter 2

21. Crime-Scene Sketch Form
All rough sketches include
Title block with information on the case, crime scene, and person creating the sketch
Legend with identity and dimensions of objects in the sketch
Compass showing the North direction
Body containing the sketch itself
Points of reference for objects can be shown by the distance measurements from two fixed points
Forensic Science: Fundamentals & Investigations, Chapter 2

22. Forensic Science: Fundamentals & Investigations, Chapter 2

23. Finished Sketch
The finished sketch is created from the information in rough sketch, but it is drawn to scale with care and concern for appearance.
The current standard method utilizes Computer-Aided Drafting (CAD) programs to create the finished sketch.
Forensic Science: Fundamentals & Investigations, Chapter 2

24. Testimony by a witness about what that witness saw, heard, or did
Types of Evidence
Direct evidence
Testimony by a witness about what that witness saw, heard, or did
Forensic Science: Fundamentals & Investigations, Chapter 2

25. Types of Evidence Circumstantial evidence Physical evidence
also called Indirect
trace evidence
Physical evidence
e.g., fingerprints
Biological evidence
e.g., blood or hairs
Trace evidence…Small physical evidence that requires a microscope or chemistry equipment for analysis is called trace evidence.
Forensic Science: Fundamentals & Investigations, Chapter 2

26. Collecting Evidence
Often, many items of evidence are clearly visible but others may be detected only through examination at the crime laboratory.
For this reason, it is important to collect possible carriers of trace evidence, such as clothing, vacuum sweepings, and fingernail scrapings, in addition to more discernible items.
Forensic Science: Fundamentals & Investigations, Chapter 2

27. Collection…
Investigators handle and process physical evidence in a way that prevents changes to the evidence through contamination, breakage, evaporation, accidental scratching or bending, or through improper or careless packaging.
The use of latex gloves, disposable forceps, and sanitized equipment reduces the chance for contamination.
Whenever possible, one should keep evidence in its original condition as found at the crime scene.
Forensic Science: Fundamentals & Investigations, Chapter 2

28. Types of Evidence Explain why this would be or
would not be trace evidence
Forensic Science: Fundamentals & Investigations, Chapter 2

29. Packaging the evidence
Crease a clean paper and place evidence in the X position
Fold in the left and right sides, and then fold in the top and bottom
Put the bindle into a plastic or paper evidence bag affixing a seal over the opening
Write your name on the seal
Forensic Science: Fundamentals & Investigations, Chapter 2

30. Evidence ID Forms
Forensic Science: Fundamentals & Investigations, Chapter 2

31. Chain of Custody
Maintaining a chain of custody log is essential to present credible evidence in court
Forensic Science: Fundamentals & Investigations, Chapter 2

32. Chain of Custody (cont’d.)
Bag the evidence Add identification Seal it Sign it across the sealed edge
Sign over to a lab technician Open bag on non-sealed edge
Return items to the evidence bag Seal evidence bag in another bag Sign the evidence log
Forensic Science: Fundamentals & Investigations, Chapter 2

33. Analyze the Evidence
Facts result from collected evidence processed by the forensic lab
Lead detective aims to see how facts fit into the crime scenario
Forensic Science: Fundamentals & Investigations, Chapter 2

34. Analyze the Evidence Lab results can:
Show reliability of witness accounts
Establish the identity of suspects or victims
Show suspects to be innocent or link them with a scene or victim
Forensic Science: Fundamentals & Investigations, Chapter 2

35. Crime Scene Reconstruction
Crime scene reconstruction involves:
Forming a hypothesis of the sequence of events
From before the crime was committed through its commission
Forensic Science: Fundamentals & Investigations, Chapter 2

36. Staged Crime Scenes
When lab results don’t match up with the testimony of witnesses
Common examples:
Staging a fire—to cover bankruptcy
Staging a suicide—to cover a murder
Staging a burglary—to collect insurance money
Forensic Science: Fundamentals & Investigations, Chapter 2

37. Staged Crime Scenes Was the crime scene staged? Consider:
Does the type of wound match the weapon?
Could the wound be easily self-inflicted?
What were the mood and actions of the victim before the event?
What were the mood and actions of the suspect before the event?
Forensic Science: Fundamentals & Investigations, Chapter 2

38. Summary
Locard’s exchange principle:
Contact between people and objects can transfer material that can determine the nature and duration of the transfer
Evidence can be direct or indirect
Physical or biological traces
A crime scene investigation team consists of police, detectives, crime scene investigators, medical investigators, and specialists.
Forensic Science: Fundamentals & Investigations, Chapter 2

39. Summary
Investigations consist of recognizing, documenting, and collecting evidence.
First responding officers identify the extent of the crime scene, secure it, and segregate witnesses.
Crime scene investigators document the crime scene.
Evidence is collected, packaged, and labeled.
The evidence is analyzed and interpreted to fit the crime scenario.
Forensic Science: Fundamentals & Investigations, Chapter 2