chain of custody
the documented and unbroken transfer of evidence
circumstantial evidence (indirect evidence)
evidence used to imply a fact but not support it directly
class evidence
material that connects an individual or thin to a certain group
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 commission
datum point
a permanent, fixed point of reference used in mapping a crime scene
direct evidence
evidence that (if authentic) supports an alleged fact of a case
first responder
the first safety official to arrive at a crime scene
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 related to the crime; where evidence is found
trace evidence
small but measurable amounts of physical or biological material found at a crime scene
triangulation
a mathematical method of estimating positions of objects at a location such as a crime scene, given locations of stationary objects
locard's principle
when a person coms into contact with an object or another person, a cross-transfer of physical evidence can occur and the intensity, duration, and nature of the entities in contact determine the extent of the transfer.
why is locard's principle important in CSI
the evidence that is exchanged bears a silent witness to the criminal act (using evidence from under a victim's fingernails to help identify the attacker)
examples of trace evidence
#NAME?
difference between direct and circumstantial evidence
direct evidence- firsthand observations such as eyewitness accounts or police dashboard video cameras
circumstantial evidence- indirect evidence that can be used to imply a fact but that does not prove it, only proves link between crime scene and a suspect
example of direct evidence
witness states she saw defendant pointing a gun at a victim during a robbery.
example of circumstantial evidence
finding a suspect's gun at the site of a shooting is presence of the suspect's presence there
who are the 5 professional people at a crime scene
#NAME?
police officer's duty at crime scene
secure the scene, direct activity, call in DA to determine whether search warrant is necessary for crime scene investigators
crime scene investigator's duty at crime scene
document the crime scene, collect physical evidence, record data, sketch scene, take photos
medical examiners duty at crime scene
determine manner of death: natural, accidental, homicide, suicidal , undetermined
detectives duty at crime scene
interview witnesses and talk to crime scene investigators about evidence
specialists duty at crime scene
consulted if evidence requires their expertise
7 steps (s's) of a crime scene
#NAME?
Securing the scene
first responder does it
safety of all individuals is first priority
preservation of evidence is second
officer protects area within which crime has occured and restricts all visitors
keeps a security log of those who visit and collects pertinent info and requests any additional requirements for investigation
separating the witnesses
witnesses cant talk to each other so they do not create a story (collusion)
CSI compare witnesses accounts of events
ask series of questions (when, who is victim, who called 911, can perpetrator be identified, what happened, where were you)
scanning the scene
forensic CSI scan scene to determine where photos should be taken
determine primary and secondary crime scenes
seeing the scene
take photos of overall area and close up photos with and without measuring ruler all including triangulation
close ups and photos from varying distances of any evidence and remains taken
sketching the scene
CSI makes sketch noting position of remains and any other evidence measured from two immovable landmarks
include north, distance scale, any other objects, outdoor objects
later a more accurate final copy is made
searching for evidence
use a type of search pattern depending on size of area and number of investigators
single investigators (gridded, linear, spiral)
group (linear, zone or quadrant)
all evidence photographed, sketched, labeled, and documented
use flashlights or black lights to locate hair, fibers, or body fluids
securing and collecting evidence
liquids and arson remains in airtight unbreakable containers
moist biological evidence in breathable containers so evidence can dry out and not mold
after air drying it is packaged in paper bindle (druggists fold) and placed in plastic or paper container
outer container sealed with tape and labeled with signature of collector
evidence log and chain of custody attached
why is securing a crime scene important
So that the evidence is not tampered with or contaminated
identify the method in which evidence is documented properly
datum points, chain of custody, evidence log
how does the chain of custody work
individual who finds evidence bags it in a plastic or paper container and puts it into a collection bag or box labeled with pertinent info and sealed with collectors signature on seal
given to next person who takes it to the lab and signs it over to technician
tech opens package at location other than sealed edge, repackages in original packaging, puts it in new packaging, signs chain of custody log
why is the chain of custody important in packaging evidence
so that it is evident that the evidence was not tampered with on its way to court and also so that if it gets messed up they know who did it
how is crime scene evidence analyzed in a forensics lab
lab processes all of evidence processed at crime scene
they are specialized and process only on type of evidence. they send it back to lead detective who looks at it and tries to fit it into the scene
evidence is examined and compared with witnesses' statements to determine reliability
4 different types of crime scene search patterns
grid
linear
quadrant or zone
spiral
why is crime scene reconstruction used sometimes
to determine whether or not a crime scene was staged
how is crime scene reconstruction done
-form hypothesis of sequence of event before crime was committed through commission.
-examine evidence and compare it with witnesses' statements to determine reliability of accounts
-look at evidence and see if it fits into crime scene
how do trained investigators figure out how a crime scene has been staged by someone
the evidence will not match the testimony of witnesses
case studies- how evidence obtained at these crime scenes was crucial to solving each case pg 34
lillian oetting- the twine tied around victim only sold at starved rock state park where Weger worked, blood on coat tested to be compatible with blood of one of victims
atlanta child murders- floor carpeting fiber only sold in 10 states (one in which Williams lived) and matched carpet in his home, car carpet fiber found only in pre 1973 chevrolets matched carpet in william's 1970 chevrolet.
careers in forensics: crime scene investigator- what duties are performed for this job and what kind of educational and/or training background is required? pg. 35
duties- arrive at crime scenes and work with first responding officer to decide what best methods are for you to obtain evidence, record scene using photography and video, gather evidence, take impressions of anyone who accessed crime scene, secure all samples in packaging to send to lab, testify in court.
training- knowledgable in areas of recognition, documentation, preservation of evidence.
education- degree in crime scene investigation, associate's or bachelor's degree in science with emphasis in law enforcement and crime scene processing or a criminal justice degree with emphasis in science