criminal investigation Flashcards
Criminal Investigations
Use Respect to conduct an objective & procedurally just criminal investigation
**begin the moment police are called to the scene
are s_tep-by-step process_ & primary goals for police officers are to:
protect crime scene & collect evidence
determine if and how a crime was committed
Identify victims & witnesses
identify the offender
write a detailed & complete report
Testify in court
Respond to the scene and make it safe
- Plan a safe response
- Take the most direct route and safest route
- In progress crimes= look for matching descriptions of people/ vehicles involved
Emergency care for injured/ wounded
- Request EMS when needed
- Establish a pathway for first responders to avoid evidence destruction
- Do not clean up or move any treatment supplies used by EMS
- Do not attempt to reposition/ return physical evidence to its original spot
- ID Persons treated on scene
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Bodily injury
- Substantial impairment of the physical condition
- Burn, fracture
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Serious bodily injury
- Creates permanent disfigurement prolonged/permanent loss of bodily function
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Injury Photo Taking
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Overall (injury photo taking)
- Take at least one overall photo of the person to include the face, injury and other unique features such as jewelry, tattoos, clothing.
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Mid-range (injury photo taking)
- Take photos of each injury from 2-4ft away
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Close up (injury photo taking)
- Take photos of each injury less than 2ft away. Place ruler or other objects to compare size
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Follow up (injury photo taking)
- Injuries may intensify over days. Take photos 2-3 days after
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Overall (injury photo taking)
Separate and remove people
- Prevent influence from other people
- Separate victims and witnesses
- ID and separate witnesses for interviewing
- Remove uninvolved bystanders
Protecting the crime scene
- The crime scene is a specific place where a crime has been committed and physical evidence is located
- Establish temporary crime scene perimeters
- Do not touch, move or alter any item within the crime scene until it has been evaluated
- Establish pathways to enter and exit
Modus Operandi (MO)
- Think motive
- “Uniqueness of technique a distinctiveness or a particularly distinguishing pattern of conduct common to the current and former incidents that link one crime to another”
Initial walk through
- Use pathways to minimize evidence contact or contamination prevention
- Identify special clothing or equipment needs for safety or contamination prevention
- ID points of contact
- Request expert investigators and forensic specialists
Points of contact
- Entry and exit
- Between suspect and victim
- Between suspect and evidence
- Between victim and evidence
Inner perimeter
- Where the actual crime took place and contains physical evidence
- Make this perimeter at least twice the size of the actual crime scene
- Use red tape for inner and yellow for outer perimeter
- Only allow authorized personnel in
- Establish a single entry and exit
- At least 2 officers should guard the entry and exit
- Establish a crime scene log
Outer perimeter
- The staging area for support personnel and equipment
- Identify perimeter with a combination of emergency vehicles, police officers, barriers and line tape
Photograph crime scene
- Provides a visual record of the scene and helps identify relevant evidence
- Use agency owned camera. Do Not use personal phone/ camera
Photograph crime scene/ evidence as found
Overall (photographing the crime scene)
- Photograph crime scene from outer perimeter first. Multiple angles/ perspectives
- Take these photos before placing markers
- For outdoor crime scenes include land markers, street signs, house numbers
Midrange (photographing the crime scene)
- Inside the inner perimeter
- Multiple angles/ perspectives
- Includes property damage and specific items, exits and entry points
- 5-10ft away
Close range (photographing the crime scene)
- Specific evidence from a perspective of less than 4ft away
- Positively identify objects (license plates, serial numbers, impression evidence)
Evidence collection
- CSI effect
- Juries are more likely to convict a suspect in an evidence based prosecution
- Chain of custody
- The meticulous and chronological documentation of evidence from the moment seized to presentation in court
- Prevents loss, destruction, tampering, and contamination
- Shows every person who came in contact with evidence
- Evidence packaging and storage
- Containers are made of paper, cardboard, plastic, and glass
- Seal containers to prevent tampering
- Evidence tags are used to identify evidence
- Store evidence in a restricted location
Types of Physical evidence
- Drugs
- Money
- Clothing
- Weapons
- Documents
- Digital files
- Fingerprints & impressions
- DNA (blood, saliva, semen)
- Trace evidence (fibers, hairs, gunshot residue)
Physical evidence
- Is tangible (things we can touch) “can be perceived by sense of touch”
- Can be direct or circumstantial evidence
- Used to reconstruct crime scenes and link people to specific places and or other people
- Items can be: drugs, money, clothing, weapons, documents, digital files, fingerprints, DNA etc.
Trace evidence
- Evidence transferred from one surface to another during physical contact between people, places, and objects
- Usually microscopic size (soil, gunshot residue, human/animal hair, paint fibers)
- Can be found anywhere and is common when there is physical contact between suspect and victims
DNA evidence
- Also known as biological evidence
- Can be: human hair, tissue, bones, teeth, blood, saliva, semen
- Best practices:
- Change gloves between every sample collected
- Package separately
- Attach biohazard label
Fingerprint Evidence
- Human skin ridge impressions left behind on surfaces (palm print or fingerprint)
- Patent fingerprint
- Seen with the naked eye and left behind when materials (like blood, oil, or dirt) on fingers is transferred to a surface
- Can be found on paper, wood, cloths, plastic, metal, glass etc.)
- Plastic fingerprint
- Seen with the naked eye and left when a person leaves an indentation in a soft surface (think pushing fingers into playdough or silly puddy)
- Can be found in soap, gum, wax
- Latent fingerprint
- Cannot be seen with the naked eye. Left behind when oil and sweat on finger skin is transferred to a smooth, non porous surface
- Exposed with special chemicals or light technology
- Patent fingerprint
Impression evidence
- When one object presses against another with enough force to leave a matching imprint
- Shoe prints, tire tracks, and human bites
Can be found in snow, blood, dirt/sand, human ski
Clothing, bedding, and linen evidence
- Items worn/used by victims/suspects
- Use paper bags, cardboard boxes, and porous items to package dry cloths
- Use non porous plastic containers to temporarily collect wet clothing
- Evidence that is wet SHOULD NOT remain inside any plastic container for more than 2 hours (can destroy/alter evidence)
- Must be air dried before storing
Weapon evidence
- Fire arms, ammo, knives, baseball bats
- Use porous material like cardboard boxes to collect and package
- Process DNA, trace, and finger print evidence first
Liquid evidence
- Should be stored in its original container if possible
Store in leak proof containers