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Chain of custody
the documented and unbroken transfer of evidence.
Circumstantial evidence
Indirect evidence that can be used to imply a fact but does NOT directly prove it, only the suspect and victim see the evidence left at the crime scene (understanding how it was used, but examiners can only IMPLY bc. they weren’t there)
Class evidence
material that connects an individual or thing to a certain group (see individual evidence).
Crime-scene investigation
a multidisciplinary approach in which scientific and legal professionals work together to solve a crime
Crime-scene reconstruction
a hypothesis of the sequence of events from before the crime was committed through its commissions
Direct evidence
evidence that (if true) proves an alleged fact, such as an eyewitness account of a crime;Firsthand observations such as eyewitness accounts or police dashboard video cameras
Individual evidence
a kind of evidence that identifies a particular person or thing
Paper bindle
a folded paper used to hold trace evidence
Primary crime scene
- the location where the crime took place.
Secondary crime scene
a location other than the primary crime scene, but that is in some way related to the crime, where evidence is found.
Trace evidence
small but measurable amounts of physical or biological material found at a crime scene
Goal of Crime-scene investigation
recognize, document and collect evidence at the scene of a crime
Who documented the crime scene and collects physical evidence?
crime-scene investigators
Typically first to arrive on scene:
police officers; district attorney may be present if search warrant is necessary
Circumstantial Evidence can be either__________
Biological (ex: body fluids, hair, etc.) or physical (ex: fingerprints, footprints, tire impressions, etc.), or TRACE EVIDENCE
What determine the extent of trace evidence?
intensity, duration, and nature of materials in contact
Example of trace evidence:
Located used evidence from under a female victim’s fingernails to help identify her attacker
Trace evidence bears a ___________ to a crime
silent witness
Who can trace evidence be found on (remember physical transfer=trace evidence)
both persons
Dr. Edmond Locard’s Principle of Exchange
When a person comes into contact with an object or another person, a cross-transfer of physical evidence can occur
Physical transfer of evidence
two people come into contact with eachother
Medical examiners role in crime-scene investigation:
determine probable cause of death
Detectives role in crime-scene investigation
look for leads by interviewing witnesses and talk to the crime-scene investigators about the evidence
Forensic Specialist such as ____________ may be consulted if evidence requires their expertise
entomologist, forensic psychologists
The Seven “S’s” of Crime-Scene Investigation
Securing the scene, Separating the witness, Scanning the scene, Sketching the scene, Searching for evidence, Securing and Collecting evidence
Securing the scene is the responsibility of whom?
police officer (first responder)
What is first priority for securing the scene? what’s second?
safety of all individuals, preservation of evidence
Separating the witnesses prevents…
witnesses working together to create a story (collusion)
Example of primary crime scene and secondary crime scene
robbery in front of a store- primary, and the home of a suspect-secondary
place of murder-primary, where course is found- secondary
Seeing the scene means_______needs to see the scene and photos of overall area and close-up photos with an without a __________ should be taken and taken at different_________.
crime scene examiner, measuring ruler, angles
In sketching the scene…
accurate rough sketch, all objects should be measured from two immovable landmarks, north should be labeled, scale of distance provided, everything included even if outside, final copy of crime scene should be made for court
Searching for evidence can depend on the number of what?
investigators
In searching for evidence what patterns should be walked?
spiral, grid, linear
In searching for evidence the locations of evidence is:
marked, photographed, and sketched
Single investigators use what pattern
grid, linear, or spiral
A group of investigators uses what pattern
linear, zone, or quadrant
What tools avoid picking extraneous (not important) material?
flashlight and forceps
In searching for evidence patterns are_____and ensure______?
systematic, that no area is left unsearched
In securing and collecting evidence, evidence needs to be_______
properly packaged, sealed, and labeled
In securing and collecting evidence liquids and arson are_____
stored in airtight, unbreakable containers
In securing and collecting evidence, biological or wet evidence is____
stored in breathable containers so the evidence can dry out and mold contamination is reduced
Biological evidence, once dried and after being stored in breathable containers, is____
packaged in a paper bindle and placed into a plastic or paper container; the outer containers is sealed with tape and labeled with the signature of the collector
Evidence is ______ by the collector
signed with his/her name
One of the largest forensic crime labs in the world
FBI crime lab
What lab processes all evidence collected
forensic lab
Who are and what do forensic lab techs do
specialized in one particular forensic field (ex:entomology) and process one type of evidence
Who are lab RESULTS sent to
the lead detective
What do test results lead to
crime-scene reconstruction
Crime Scene Reconstruction
Forming a hypothesis of the sequence of events from before the crime was committed through its commission.
Who determines how evidences fits into the overall crime scenario
detectives
Evidence is explained and compared to what to determine the reliability of what?
witnesses’ statements to determine the reliability of their accounts
Acquit
free someone from a criminal charge by a verdict of not guilty
Evidence doesn't lie but can be_____
staged
Common situations in which a crime scene is staged
arson (often used to cover up other crimes like murder), suicide/murder (can be staged to look like a suicide), burglary (staged to collect insurance money)
