Crime Scene Investigation Methods

Scene Control

• When CSIs arrive, those in control could be Detectives, First Responding Officers, or other units/agencies.
• Processing considerations start with initial contact/notification.
• Processing refers to the treatment or preparation of objects, surfaces, and locations.

Scene Processing

• Collect as much information as possible for evidence.
• Evidence is a function of interrelationships, conditions, layout, and documentation of transient/conditional evidence.

Crime Scene Investigation Methodology

• Methodology is similar but varies depending on the steps.
• Be confident, drawing on knowledge, education, training, and experience.
• Use skills/tools and have education and training in them.
• Follow a systematic and methodical approach and stay on track.
• Maintain flexibility because the method could be interrupted.
• Ensure a coordinated effort within the CS team and between investigators and crime scene personnel.

Crime Scene Investigation: Integrity

• Part of knowledge is understanding potential contamination, degradation, and changes.
• There can be addition of, destruction of, and movement of material to/in the scene.

Addition of Material

• Post-incident artifacts can be added.
• Action must determine post-incident material which is relevant.
• Important to question first responding officer(s) for footwear impressions, food/drink containers, cigarette butts, DNA, or fingerprints.

Destruction of Material

• Material can be lost between the incident conclusion and first response time.
• Once something changes, it cannot be recovered.
• Evidence may be located on the perimeter.
• First responders/witnesses present can cause loss of evidence, trace evidence on body, or alteration of pattern evidence at entrance/exit points.

Movement (Alteration) of Material

• This can be the result of emergency or investigative actions.
• Once something changes, it might not be retrievable.
• "Know who did what" and why.
• Examples include removal of fractured items from MVAs, removal of items from suicides, change in conditional evidence, or movement of weapons.

Methodology

• Purpose is to reduce the potential for addition, destruction, or movement of material.
• Methodical actions can still cause some destructive/altering aspects.
• Start with the least intrusive action and end with actions causing the most change, moving from general to focused.
• Following a basic order of six activities:
  • Assess
  • Observe
  • Document
  • Search
  • Collect
  • Analyze

Assess

• Allows investigator to determine a plan of action.
• Consider scene complexity, fragility of evidence, resources required, inherent risks/mitigation strategies, and flexibility.

Observe

• The most common activity is the mental registration of conditions and artifacts.
• Be aware of movements, start "big" and then move in.

Document

• Four methods: notes, photos, videos, and sketches/measurements.
• Documentation must be done in this order: notes, photos, videos, and sketches/measurements.
• Documentation happens in situ.

Search

• An intrusive investigation.
• Alterations occur during searching.
• Visual and "Hard" searches can be done in stages.

Collect

• Extremely intrusive, with a different level of alteration.
• Once the evidence is collected, it can't be un-collected.
• Occurs only after documentation, except in fragile or exigent circumstances.

Analyze

• A multi-step process.
• Employ large-scale, scene-changing processing techniques:
  • Fingerprint development
  • Chemical enhancement
• Submission of evidence to a forensic laboratory is also involved.

Working Backwards

• Always prepare to go back to a prior step because it is normal and could mean something was missed.

Step 1: Initial Notification

• Can start differently and may not be the call expected, so expect the unexpected.
• Document everything, tracking all discrepancies.

Step 2: Coordination, Assessment, and Team Callout

• Check the scene for complexity and the required resources.
• Contact extra CSIs and the fire department if necessary.
• Collect lights, camera equipment, safety equipment etc.
• Verify the scene location.
• Document environmental conditions.
• Find first responding officer(s).

Step 3: Conduct Initial Walk-through

• Look but don't touch Victims, Fragile evidence, Areas of entry/exit, Obvious signs of damage or change.
• Establish whether the scene is primary or secondary.
• Consider exigent circumstances for documentation/collection.
• Use one path with 1-2 people at a time to reduce alteration of material.

Step 4: Document Overall Observations

• Documentation continues through the examination, starting with the initial notification.
• Includes first responder information, who is/was on the scene, conditional/transient evidence, positions of objects/bodies, actions by first responders, etc.

Step 5: Photograph/Video Documentation

• Photographs/Videos function as pictorial representations of the scene.
• Proceed from overall to mid-range, to close-up. This is an ongoing process.
• Photograph in situ and fragile evidence first.
• The viewer must understand the overall conditions/context.

Step 6: Identify and Mark Evidence

• Create a list of evidence for presumptive tests after overall photos.
• Inform the team and mark the evidence with tents to note things like Nike Air Jordan high top sneaker, right shoe, size 9, Two swabs from blood-like substance on front door knob, One white Samsung S22 with clear cover, One brown glass Budweiser beer bottle, or Two swabs from kitchen cold water knob, kitchen sink.
• There is no importance placed on what order the items are examined in.

Step 7: Sketch/Mapping

• Photo/Video documentation take a break at this time.
• Written notes should capture the exact positions and locations of evidence.
• Use two people at minimum for hand-sketching.
• Sketches should include room shape with dimensions, openings, furniture with dimensions, and evidence fixed with mapping methods.

Step 8: Evidence Collection

• Close-up photographs and video must be done prior to collection.
• The evidence can be extremely fragile.
• Collect what is around the deceased first.
• Fully fill out the log and, if there isn't log use written notes instead.
• Place container to evidence and order does not matter.
• What matters is; Appropriate containers, time of collection, and the name of the collector.

Step 9: Deal with the Deceased

• Notify medical examiner/coroner if they have not been notified yet.
• Write down pertinent information when the MDI (medico-legal death investigator) arrives on scene.
• Capture, Name/ID, Agency and Time of arrival.
• Do not manipulate the body is prior to the investigators arrival.
• Make note of any observations of manipulation of the body, and communicate it to authorities.

Step 10: Deal with the Deceased

• Release the deceased to medical examiner/coroner personnel or trade service.
• Do not rush the process and ensure everything is documented, measured checked and collected.
• Cover the deceased with paperbags to protect them.
• Use a body with ALS for biological stains or other trace evidence and obtain permission to take items.

Step 11: Conduct First Hard Search

• By this point all evidence from the visual search ought to be stored in the correct containers.
• Increase in intrusive action, ensure that you move each item in a systematic order.
• Just one person can coordinate the entire search.
• Determine the search method and assess if any additional equipment is needed.
• Be cautious and vigilant and nevery put your hands where you cannot visually see.
• For this use light, Flashlights, portable lights and an ALS.

Step 12: Document and Collect New Evidence

• Following the discovery of new evidence, document it using all available methods.
• Each item can be done individually or when the search is finished.
• Evidence marjers are also scales are agency specfic so assess what needs to be used.

Step 13: Conduct Re-check/2nd Hard Search

• When dealign with additional ever review checklists and repeat steps.
• If a area is missed ensure to document this area.
• The search coordinator can ensure the rest of the team are vigilant.

Step 14: Employ Processing Techniques

• As this part is extremely intrusive always do it here.
• Methods that can be used include Fingerprinting, chemical development, trajectory analysis, chemical enhancement and blood pattern analysis.
• These practices most be well documented.

Step 15: Check Beyond the Scene

• Can occur in multiple environments, Yard, city block, field etc.
• If the enviroment is to dangerous, make note of it.
• Assess how many people are available and deal with new evidence accordingly.
• Be aware if a patter and or chemical enhancement is needed.

Step 16: On-Site Debrief

• Ensure this is followed prior to releasing the scene.
• Take a break with the entire group and discuss what has happen while giving assignments.
• Comparying notes can allow individuals to assess if any information does not align.

Step 17: Release the Scene!

• When it has been assured that all steps are done the scene can be released.
• If possible get a have the action to to be confirmed twice.
• Check that all the controll samples have been secured and determine if there is any further actions to take.
• In the event of any doubt, ensure the scene remains secured.

Post on-scene investigation

• There are multiple agency specified acitivities however common methods include;
  • Debriefing with investigators, Meeting with medical examiners.
  • Examine documentation and secure KOWN samples.
  • Undertake discussions with laboratories and secure warrants.