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 thing to a certain group
crime-scene investigation
a multidisciplinary approach in which scientific and legal professionals work 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;
typically police officer
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 exchange principle
when a person comes into contact with an object or another person, a cross-transfer of physical evidence can occur; the intensity, duration, and nature of the entities in contact determine the extent of the transfer
why is locard's principle important in csi
it keeps evidence from being contaminated
examples of trace evidence
hair, fibers, glass, dirt, fingerprints, soil, pollen, bodily fluids, debris, paint chips, chemicals
example of class evidence
blood type gives us a group of people that fit the sample of blood from the scene
example of individual evidence
fingerprints and dna give us a specific person
examples of direct evidence
witness account, police dashcam video, confession
examples of circumstantial evidence
suspect's gun found at a shooting, fingerprints, shell casings
5 professionals at a crime scene
police officers, crime-scene investigators, medical examiners, detectives, specialists
police officers
first to arrive at a crime scene, secure the scene, direct activity, district attorney may be called to the scene to determine whether a search warrant is necessary for the crime-scene investigation
crime-scene investigators
document the crime scene in detail and collect physical evidence, record the data, sketch and take photos of the scene
medical examiner (coroner)
own the crime scene until the body is removed from the scene
detectives
interview witnesses and talk to crime-scene investigators about the evidence
specialists
entomologists (insect biologists), forensic scientists, forensic psychologists
****most likely to show up to the scene first
police officer
7 s's of csi
secure the scene, separate the witnesses, scan the scene, see the scene, sketch the scene, search for evidence, secure the collected evidence
secure the scene
first priority is safety of all individuals; officer protects the area within the crime scene and restricts unauthorized people from entering; transfer, loss, or contamination of evidence can occur if the area is not secured; officer keeps security log of
separate the witnesses
not allowed to talk to each other or work together to create a story, crime-scene investigators will compares witness accounts
scan the scene
scan primary and secondary scene to see where photos should be taken
see the scene
photos of the overall area and close up, with and without a measuring ruler, triangulation should be included in photos, photos of evidence and remains
sketch the scene
triangulation; rough sketch includes reference points, legend, compass; final sketch is detailed and to scale; label doors and windows and the direction they open in; arrow shows which direction the stairs go in
search for evidence
quadrant/spiral search used for interior crime scene with clear boundaries; grid search used for exterior or intricate interior; linear search can be used by multiple investigators
secure the collected evidence
evidence is photographed, collected, and stored; identify time of collection, how it was packaged, who packaged it, and the placement of the item after collected; trace evidence is collected in unbreakable pill bottles, vials, boxes; blood-stained materia
why is securing a crime-scene important
safety of all individuals is the first priority; transfer, loss, or contamination of evidence can occur if the area is not secured
chain of custody
the method in which evidence is documented and shared among investigators
why is chain of custody so important to a trial
if the chain of custody is broken, it is useless in the trial and they will throw it out
how does the chain of custody work
the person who finds the evidence bags it in a plastic or paper container. the final container for evidence is a collection bag or box, which is labeled with the pertinent info. the container is sealed and the collector's signature is written across the s
why is chain of custody so important in packaging evidence
so you know who had the evidence when
how is crime scene evidence analyzed in a forensics lab
the lab processes the evidence and the lab results are sent to the lead detective. lab techs are specialized and process only one type of evidence
quadrant search
used for interior crime scene with clear boundaries
spiral search
used for interior crime scene with clear boundaries
grid search
used for exterior or intricate interior
linear search
used by multiple investigators
why is crime-scene reconstruction sometimes used
helps investigators form a hypothesis of what happened before and during the crime and if the witnesses' statements are reliable
how is crime-scene reconstruction done
...
process of crime-scene sketch
establish fixed points, measure and mark evidence positions, legend, compass, do a rough draft at the scene
how can trained investigators figure out how a crime-scene has been staged by someone
treat all death investigations as homicides, are the wounds on the victim consistent with suspected weapon, could the wounds be self-inflicted, establish a profile of the victim, evaluate behavior of victim and suspects before the event, corroborate state
examples of staged crime-scene
arson, murder looking like a suicide, burglary
why would someone stage a crime-scene
insurance money, release from an unhappy marriage, robbery, to cover up a murder
things that went wrong in jonbenet ramsey case
officers did not secure the scene, unauthorized officials went in and out of the scene, evidence was moved, victims body was moved, family fled the state, not enough staff because it was the day after christmas
evidence that seemed confusing or weird in jonbenet ramsey case
2.5 page long ransom note, ransom note included exact amount of the father's bonus that year,
case studies page 34
...
careers in forensics: csi page 35
...