physical evidence and crime scene Flashcards
What do you package things with body fluids in?
Manila folder/paper bags
NO PLASTIC
What is evidence?
- Testimony, records, documents, material objects, or other things presented at a trial to prove the existence or nonexistence of fact
- Evidence is the exchange of material between two persons, persons to things, or things to things
What is physical evidence?
(physical vs testimonial)
Any objects that can establish that a crime has been committed or can provide a link between a crime and its victim or a crime and its perpetrator
What are the types of crime scene photography and their purpose?
(Three types)
Overviews
* Widest view of scene
Mid-views:
* Location of evidence in room in relation to other evidence
Close ups:
* Detail a piece of evidence (with scale)
What are the cognitive errors in drawing conclusions?
Confirmation bias:
* The tendency to search for, interpret, and remember information in a way that confirms one’s preconceptions
Anchoring bias (parts per toto):
* Relying too heavily on the initial piece of information (the anchor) when making decisions
Burden of proof ”onus probandi”:
* Shifting the burden of proof from the investigator to the suspect
* The suspect must prove innocence rather than prosecution proving guilt
What do you package hair/fibers in?
Paper bindles in envelopes/folders
What is the crime scene scientific process?
Crime scene
* Collection and preservation of evidence
* Submission to lab
* Evaluation of results and report
Trial
When do you use a spiral search?
- In a small space
- When alone
The CSI arriving on scene should first:____
- Evaluate the area and make sure it is secure
- Conduct an initial walk through of the scene
- Take immediate note of details
- Define extent of crime scene
- Develop a plan for examining and documenting the entire crime scene
What do you package firearms in?
- Gun case
- Plastic (without ammunition and clip)
When do you use a grid search?
- In large spaces
- When multiple people are available
What is direct evidence?
(direct vs circumstantial)
- Establishes “directly” the fact of the information
- Does not need to infer anything regarding the evidence
Types: eyewitness, crime scene photography, ID of a powder as an illicit drug
What are class characteristics?
(class vs individual evidence)
class: properties of evidence that can be associated only with a group, never with a single source
- It’s a blue car
- Fiber
- Body fluid (not DNA)
What is the crime scene legal process?
Crime scene
* Warrant documentation
* Investigation
* Admissibility in court
Trial
What are the classifications of evidence?
- Physical evidence
- Testimonial evidence
- Direct evidence
- Circumstantial evidence
- Reconstruction evidence
- Associated evidence
What is associative evidence?
(reconstruction vs associative)
- items that are considered of unknow or questionable origin until a comparison is made to a known standard or exemplar
- helps link a person to a place
What do you package volatile evidence in?
Paint cans (prevents evaporation of fumes)
What are the types of examination of physical evidence?
- comparison: determining whether two or more objects have a common origin
- Identification: determining a substance’s physical or chemical identity
The first officer on the scene should:____
- Call for medical assistance or make arrests
- Secure and isolate the core area of the crime scene from unauthorized personnel
What are the best conditions for storing evidence?
Cold and dry
When do you use a strip search?
- When under a time constraint
- In a large space
- Multiple people present
What are the types of documentation?
Why do we document?
(Four types)
Types of documentation:
* Photography
* Video
* Notes
* Sketch
Reasons to document:
* Create permanent record
* Investigative report
* For presentation at trial
What are the crime scene search methods?
(Four types)
- Zone/sector search
- Spiral search
- Strip search
- Grid search
What is circumstantial evidence?
(direct vs circumstantial)
- Can infer additional information
- Inferring the individual was at the scene and sexual activity occurred
- but does not imply they are guilty of sexual assault
Ex. Defendant’s semen is found on the victim, therefore links their DN to crime scene
Examples of classifications of evidence:
(Eyewitness, bloodstain, and cocaine)
- Eyewitness: testimonial, direct, and reconstruction
- Bloodstain splatter: physical, circumstantial, reconstruction
- Cocaine powder: physical, direct, associative
What are individual characteristics?
(class vs individual evidence)
Individual: properties of evidence that can be attributed to a common source with an extremely high degree of certainty
- license plate number
- DNA in a strand of hair
- Striation marks on a bullet
- Fingerprint
What are the types of interpretations of evidence?
(three types)
Deductive:
* General idea to make a specific conclusion
Inductive:
* Using a specific case to make a general conclusion
Abductive (most used):
* Proposes the best possible explanation (hypothesis) for specific observations
When do you use a zone search?
In rough terrain outside
In a small space
What is reconstruction evidence?
(reconstruction vs associative)
provides information about the events preceding, occurring during, and after the commission of a crime
What happens once evidence is collected?
It is:
* Tagged
* Signed and sealed
* Logged in the crime scene log
What is the general process at a crime scene?
- Secure and isolating the crime scene
- Crime scene processing
a. Preliminary survey
b. Official documentation
c. Search
d. Evidence collection - Final survey and release of the scene
What should be considered during the preliminary walkthrough?
- Establish scope of crime
- Document
- Identify perishable evidence
- Look for entry/exit points
- Plan for further processing
What are the results of comparison?
(There are 3)
- Inclusive: include as a possible source
- Ex. The DNA from the door handle matches the DNA of the suspect
- Exclusive: not a source
- Ex. The DNA from the door handle does not match the SNA of the suspect
- Does not mean innocence, but does not mean proof either
- Inconclusive: neither include nor exclude as a possible source
- Ex. Not enough DNA was collected from the door handle
What can you package evidence in?
- Manila folders
- Druggest fold/paper bindle (put in folder)
- Paper bag
- Plastic bag
- Glass vial or pill bottle
- Paint can
- Gun box
What do you package drug residue in?
Druggest fold/paper bindle in manilla folder
