Forensic Science and Physical Evidence

• Physical evidence encompasses any object that can establish or disprove a crime, or link a crime to its victim or perpetrator
• Crime laboratories rely on physical evidence in order to function
• Physical evidence requires recognition at the crime scene to be effective
• Selectivity in collecting physical evidence relies on the collector's knowledge of crime laboratory techniques, capabilities, and limitations

Forensic Science Techniques

• Forthcoming chapters delve into methods and techniques for forensic scientists to evaluate physical evidence
• Recent technological advancements in crime laboratory capabilities should not lead to complacency among criminal investigators
• Thorough investigations by professional police officers are essential for enhancing the chances of a successful outcome
• Forensic science is an important aspect of the investigative process that requires teamwork

Crime Scene Investigation

• Proper crime-scene search know-how is accessible to any police department with proper training
• Some police agencies use specialized technician teams
• Crime-scene investigation techniques are not difficult to master
• Limited resources have led some police agencies to restrict their efforts to serious crimes
• Fundamental practices must be followed when processing a crime scene for physical evidence

Securing and Isolating the Crime Scene

• The first officer on scene preserves and protects the area, relying on training to deal with violent or hazardous situations
• Note vehicles/people leaving the scene
• Priority is given to medical assistance/apprehending the perpetrator
• Efforts should be made to exclude unauthorized personnel
• Medical workers are directed to approach bodies indirectly to minimize disturbance
• The first responding officer must evaluate the victim's condition and record any statements
• Boundaries should encompass the center, paths of entry/exit, and areas where evidence might have been discarded or moved
• Ropes/barricades and guards prevent unauthorized access
• Efforts include identifying all individuals/detaining potential suspects or witnesses
• Compassion is shown to family/friends of the victim, but they are excluded
• Only assigned investigative personnel are admitted
• Responding officers accurately log who enters/exits the scene and when
• Violent crimes get attention from higher-level police officials, members of the press, emotionally charged neighbors, and curiosity seekers
• Individuals who enter the scene can unintentionally destroy physical evidence
• An officer responsible for protecting the scene must have the authority to exclude everyone, including fellow officers
• Trained criminal investigators are always prepared to relate crime scene horror stories where physical evidence was rendered valueless
• Critical investigative steps are to secure and isolate the crime scene and the accomplishment shows a trained and professional investigative team

Crime Scene Evaluation

• Once the scene is secured, a lead investigator evaluates the area
• First, the lead investigator determines the boundaries and perpetrator's entry/exit path
• Obvious crime-scene evidence first comes to the investigator's attention
• The investigator documents and photographs the obvious evidence
• The investigator does a scene walk-through to gain an overview and develop a systematic strategy

Body-Worn Cameras

• Racial tensions have pushed the issue of police body cameras
• Body cameras can be snapped onto a uniform or pair of glasses and monitor efforts to secure a crime scene in real-time
• The primary concerns of body worn cameras revolves around data storage and management
• They will not replace traditional digital and video cameras at crime scenes
• Personnel aren't to do anything that alters the scene, including smoking, eating, drinking, and littering
• Aspects of the scene, including bodies, are not to be disturbed unless they pose a serious threat to investigating officers or bystanders
• One isn't to open/close faucets or flush toilets, or alter temperature conditions by adjusting windows, doors, or the heating/air conditioning

Crime Scene Recording

• The opportunity to document the original state may not be lost
• Records prove useful during subsequent investigations/are required for presentation at trial
• Records document the crime site condition and delineate physical evidence location
• Notes, photography, and sketches are methods for crime-scene recording, ideally all three should be employed
• Departmental guidelines establish priorities for photography use, and circumstances prohibit the use of photography at every crime site
• Sketches and notes should be taken when photography is not used

Note-Taking

• Begins with the call to a crime-scene investigator, identifying the caller, time, and preliminary information
• Details to note include:
  • Date and time of arrival
  • Names of personnel present, titles and time of arrival
  • Record of personnel movements
  • Interview of the first responding officer to record his/her movements
  • The tasks assigned to each team member
  • Start and end times for processing the scene
• Before sketching, photographing, or searching the lead investigator carries out the initial walk-through
• All aspects of the scene should be noted during the walk-through
• Notes should be uniform, in ink (preferably black or blue), and written in a bound notebook
• Notes are to be written at the time of investigation, not from memory
• The team members mark the location of all evidence and fully describe each item in their notes once a search for evidence has taken place
• If a victim is at a homicide scene, the investigator should observe and record the state of the body before the medical examiner/coroner moves it
• Any preliminary identification of a victim/suspect should be recorded
• Audio-recording can provide detailed notes faster, leaving hands free for other tasks
• Digital voice recorders can be used but must be copied to a disk for a hard copy
• Another method is narrating a video of the crime scene, combining note-taking with photography
• The video must be transcribed into a written document
• Employing a crime scene checklist for documentation helps ensure important information is observed and collected.
• Checklists can ensure all necessary/important information is observed and collected
• Checklists can be crafted that contain general information for every type of scene, and specific information to unique scene types

Photography

• Photography must be unaltered
• Objects should not be moved unless injured individuals are involved
• Positions of objects should not be changed
• Items should not be reintroduced into the scene
• This avoids photographs that may be inadmissible
• The fact should be noted in the report if evidence has been moved or removed
• Photographs record the scene layout, evidence position, and relationships between objects
• Show possible lines of sight, photograph from many angles
• Accurate descriptions should be available for future analysis
• Photographs document biological evidence in its original condition
• Photographs are complementary to notes and sketches
• Digital cameras document crime scenes
• Used commonly in the field of forensic science

Digital Photographs

• Digital photograph-making happens when a light-sensitive microchip inside a digital camera is exposed to light
• Light is captured on each of millions of picture elements called pixels
• The light is recorded on each pixel as a specific electric charge
• Charged coupled device (CCD)/ complementary metal oxide semiconductor (CMOS) is used
• The camera reads this charge number as image information
• Resolution is directly related to the number of pixels
• Resolution = the minimum distance that must separate two objects in order for them to be viewed as distinct objects
• Greater detail and sharpness results in increasingly higher resolution photographs
• More pixels are featured on the digital camera
• Millions of pixels on digital cameras are usually referred to in terms of megapixels
• Four-megapixel camera creates a clear image on a photographic print of up to 8 by 10 inches
• Greater clarity is reached as the number of megapixels increases
• Allows photographers to create bigger prints
• Crime-scene photographers commonly use cameras that feature as many as 12 megapixels or more

Criticisms of Digital Photographs

• Digital images are opened up to criticisms within forensic science casework
• Manipulations are easily done by using computer software
• Manipulation goes beyond enhancement such as adjusting brightness and contrast or color balancing
• Main function is to provide an accurate depiction, this is a major concern
• Many jurisdictions set guidelines/establish image security and chain of custody protocols to ensure digital images are admissible

Photographic Procedures

• Crime scene must be photographed as completely as possible
• The crime-scene should include the area in which the crime took place and all adjacent areas where important acts occurred
• Points of exit and entry, should be taken from various angles
• Entire area should be photographed if crime took place indoors
• Close-up photos are also necessary
• Document injuries/weapons lying near the body
• The surface beneath the body should be photographed after the body is removed
• Items of physical evidence are discovered
• The overviews are taken after Physical evidence is photographed to show position/location relative to the scene
• Close-ups record the details
• A ruler/measuring scale may be inserted near the object and included in the photograph as a reference point
• Minimum of four photographs are required at a crime scene:
  • Overview
  • Medium-range
  • Close-up
  • Close-up with a scale
• There is an adequate visual record of the position and appearance of an item of evidence at a crime scene
• The digital revolution brings enhanced photographic capabilities to the crime scene.
• Individual images can be stitched together to reveal a nearly 3-D panoramic
• Aerial photography with drone technology is assisting the investigation of crime scenes
• There are new and elegant approaches to document the crime scene in the digital era

Digital Video and Photography

• Photographic and laser data can be combined to produce 3D models of the scene.
• Full-color scenes can be viewed from any vantage point measured, and used for analysis and courtroom presentations
• Digital video use is becoming increasingly popular as the cost of this equipment is decreasing
• Digital video includes the entire scene and the immediate surrounding area, just as used in crime-scene photographs
• Long shots as well as close-ups should be taken in a slow and systematic manner
• Has one crime-scene investigator narate events while another performs the shooting
• Cameras shake during filming, though some have stabilization features
• Zooming and panning can be sloppy
• These techniques should be used only occasionally and done very slowly
• Extra noise due to wind or other investigators can obscure narration or may be inappropriate and damaging.
• Investigators may stumble over words due to the "on the spot" nature of the narration, and may be confusing when a video is used in court
• Some investigators record the video with the sound off and dub notes over it later
• Still images of videotape are poorer than those taken by a digital camera
• Video can capture the sounds and scenes of the site, the technique is not used in place of still photography
• Stills remain unsurpassed in defining details for the human eye
• Modern video cameras often allow the user to play back recordings
• Many cameras take still photographs and video - combination of notes and photography

Body-Worn Cameras Controversy

• Relations between police and community have been controversial in the last few years due to use of excessive force
• Police officers are being called to wear body worn cameras (BWCs)
• Increased Federal Aid to make accessible to Departments
• Dramatic increase in the use of BWC’s by law enforcement individuals
• Increased legitimacy and accountability of law enforcement and the public

Functions and protocols of body worn cameras

• BWC have a microphone and data storage with video footage that is compatible with the equipment’s software
• Every police officer Can be Outfitted small camera that is easy to operate and is lightweight
• Training Is quick and the cameras can be activated and deactivated by the press of a single button
• Policy variations due to the variations in the technology and diverse companies, and regulations exist to follow protocol
• BWCs are used to collect evidence and record crime scenes/ Security and medical care demands can override crime scene documentation
• BWCs will record and document the timeline of the scene for the officer as he performs other tasks
• The footage provides the exact dynamics of a crime scene just as it was found, and the location of different objects by proximity to each other
• Can prove that evidence was collected properly tamper by the processing officer

Sketches

• After photos are taken, the crime-scene investigator sketches the scene
• The sketch serves functions in the legal investigation of a crime
• If done correctly, a sketch clearly shows the layout of an indoor/outdoor crime scene and the relationship in space
• Sketches illustrate collected evidence location
• From a good sketch, possible paths of entry, and movement through the scene may be speculated

Sketching

• The skill nor the time may be on the side of the investigator
• Rough sketches contain a good dimensions of the scene with all scene objects
• Sketches have recovered Items of Physical evidence as well as other important features of the crime scene
• Distance measurements from 2 fixed scene points are used
• Distances must be accurately measured and not guessed or estimated
• The simplest way is designation A number or letter Legend lists below sketch correlates to the item’s description

Designating sketches

• A compass designates north.
• A designator of the scene location.
• Unlike rough sketches-finished sketches reflect Information.
• Contains what was written rough sketch
• Predrawn intersections.
• Roadways or Buildings for where the information can be entered

Computer-Aided Drafting

• Computer-aided drafting is the new reconstructed norm
• Low/complex/ expensive programs
• pre drawn Intersections
• Roadways / building/ and rooms where information can be entered

Conducting Systematic Search for Evidence

• The search from physical evidence at a crime scene Thorough and Systematic
• rely on the unbiased Training and Experience
• One must Conduct a physical search right away
• can lead to negligence, if the agency knowingly "covered up" what didn't matter

Crime Scene Search

• The function is a function of the investigator in charge the scene
• Forensic scientists may not be present during crime scenes
• Some police have trained technicians to search at the crime scene
• They have the equipment and skill to check fingerprints, footprints, tool marks, or other relevant evidence
• Search patterns are Dependent Upon the suspects actions, victim’s and the scene itself
• One should Supervise and Coordinate the collect of of evidence.
• It also atmosphere with Confusion with no effort,

Search Patterns

• Strip/Line- Boundary/One end (the other investigator Starts then goes in across
• It has to be well established because the boundaries dictate the end of a search
• It also well you have to take in consideration where the boundaries are
• The boundaries that is the grid Method, two people start from adjacent corners and a Perpindicular lines
• Spiral- inward Spiral, area Light to where more evidence should most likely to be located at
• inward or outward can easily lead the footprints of the direction
• The wheel /ray
• Several people move from Boundary to Center( or Vice Versa) the areas in between the Rays are not searched ( Not Preferred)

Locating Physical Evidence and Other factors

• The Quadrant is best for dividing scene into sections and team members are assigned
• ( Small group has areas where have Small teams search with The thoroughness.
• Large/areas are Suitable Points to be noted for exit point to criminals
• Skills
• For recognition Is Successful During crimes

Homicides

• The search will Center a weapon
• Assault left between between the victim and the assailant in a cross transfer of evidence
• Such as hair/fiber, and blood
• Suspects linked to the crime scene
• Tool marks at the point of Entry
• Thru and systematic searches
• Vehicles checked Carefully planned and carried OUT

Detailed Searches

• Detailed cases determine how much must be searched
• hit and run cases, check the undercarriages and outside
• For transfers car to victim such as paint or broken glass
• Or traces such as blood from The victim
• homicide has a burglary and/Or kidnapping all areas inside and out are equal to the search for care Physical