Forensics: Exam Prep Flashcards
What is Ballistics?
Ballistics is the study of firearms, bullets, and the travel of projectiles in flight
Dactylography
Is the study of fingerprints for identification purposes
Forensic Anthropology
Identification of persons or personal characteristics (sex, age, race, stature) based on body remains
Forensic Computer Science
Investigate criminal use of technology and electronic records
Forensic Engineering
Investigates transportation accidents, and materials failure cases, determine cause of building and structure collapses, etc
Forensic Entomology
Uses insects to determine the time of death of a corpse
Forensic Odontology
Dentists who specialize in identification perform bite mark analysis and dental identification when there is no other way for body identification
Forensic Pathology
Studying medical history, performing an autopsy, and collecting medical and trace evidence from the body helps to determine the cause and circumstance of death
Forensic Psychiatry and Psychology
Evaluate offenders and profile criminal cases
Forensic Serology
Identification of blood and other bodily fluids (semen, vaginal fluid, and saliva)
Forensic Toxicology
Determines toxic substances in the body includes drugs and poisons
Forensics of Criminalistics
The study and application of science to matters of the law
Polygraphy
Conducts polygraph (lie detector) tests; administered by people trained in investigation and interrogation
Who was Bertillion?
Father of Criminal Identification; developed anthropometry which uses body measurements to distinguish individuals
Who was Galton?
- Published Finger Prints
- Conducted first distinctive study of fingerprint and their classification, gave proof of their uniqueness
Landsteiner
- Discovered the ABO blood groups
Locard
- Created the first crime lab in France
- Developed the theory every criminal can be connected to a crime from evidence
Jeffreys
- The process of DNA fingerprinting was invented (DNA profiling)
What is direct evidence?
- First-hand observations
Ex. eyewitness, video, confessions
What is circumstantial evidence?
- Indirect evidence that can be used to imply a fact but does not directly prove it
Ex. finding a suspects gun at a crime scene is evidence that the suspect was there
What is individual evidence?
- Narrows down the suspect to one person or thing
Ex. DNA, fingerprint, handwriting and sometimes physical matches
What is class evidence?
- Narrow evidence down to a group of persons or things
Ex. blood type
What is trace evidence?
- Small but measurable amounts of physical or biological material
Ex. hair strand, fingerprint, DNA, drop of blood, pollen, gunshot residue
What are the seven S’s of CSI
- Secure the scene
- Separate the witnesses
- Scan
- See
- Sketch evidence
- Search for evidence
- Secure and collect evidence
Securing the crime scene
The first officer must make sure the scene is secure by making sure all individuals in the area are safe and second by preserving evidence
- Obtain medical assistance if needed
- Arrest suspects
- Isolate the area (exclude all unauthorized personnel, put up tape ropes barricades, prevent the loss of evidence)
- Request additional needs for investigations
What is the Innocence Project
- Was created in 1992, the goal was to reexamine post-conviction cases
- helps to exonerate the wrongfully accused
What to include in a crime scene sketch
- North should be labeled, and a scale of distance (how large the area is)
- All important objects (weapon and body) should be measured from the immovable landmarks
- Any other objects in the vicinity of the crime should be included in the sketch (ex. doors, windows, furniture, trees, vehicles, etc)
- Also include the date, time, location, case number, and names (sketches and verified)
What containers do you use for trace evidence?
Plastic pill bottles in which trace evidence can be hairs, glass, fibers, etc
Where are liquid and arson remains stored?
Airtight, unbreakable containers like metal paint cans to prevent evaporation
How should you package bloodstained materials?
Packaged in wrapping paper or paper bags to prevent mold
How should you package biological evidence?
Stored in breathable containers after air dried, packaged in paper bindles (druggists fold), then in paper or plastic container
What is the chain of custody?
- A list of all persons who came into possession of an item of evidence
- Each person who comes into contact with a piece of evidence must use proper procedure and protocol in order to maintain responsible handling of evidence from crime scene to courtroom in order for the evidence to be admissible in court
Locards Exchange Principle
- Whenever two objects come into contact with one another, a cross-transfer of physical evidence can occur
- The intensity, duration, and nature of the materials in contact determine the extent of the transfer
- Every criminal can be connected to a crime by small particles carried from the scene
- EVERY CONTACT LEAVES A TRACE
How to collect evidence
Packaging evidence:
- Metal or plastic forceps may have to be used to pick up small items
- Different containers for diff types of evidence (in other questions)
- An evidence log (includes a description of the evidence, name of the suspect, name of victim, date and time of recovery, the signature of the person recovering the evidence)
- Chain of Custody
How to prevent contamination
- Should wear gloves and avoid handling evidence, only touch in areas least likely to contain latent prints
- Keep cool and dry
- Keep out of direct sunlight
- Use facemasks
What are patent prints?
Visible prints, are left on a smooth surface when blood, ink, paint, grease, or some other liquid comes into contact with the hands and is transferred to that surface
What are plastic prints?
Indentations left in some soft material such as clay, putty or wax
What are latent prints?
Are not visible to the eye but can be made visible using chemicals and are caused by the transfer of oils and other body secretions from pores onto a surface
What is the fingerprint database?
Automated Fingerprint Identification System (AFIS), which provides digital, automated fingerprint searches, latent searches, and electronic storage of fingerprints and contains over 50+ million fingerprint records
What does Ninhydrin do?
- It is a chemical that bonds with the amino acids in sweat and will produce a blue or purple colour
- It is used to lift prints from surfaces such as paper
What does one use Cyanoacrylate Vapor for?
- It reacts with amino acids
- This fuming method (also called the superglue method) is a procedure that is used to develop latent prints on a variety of objects (turns prints white) like when glue dries
What is silver nitrate used for?
- Reacts with chlorine from salt (NaCl) in sweat and combines with silver nitrate to form silver chloride
- 2 part process: first spray, then expose to sun
- Turns black or red-brown
- For wood or styrofoam
What is iodine fuming used for?
- Iodine combines with carbohydrates
- In a vapor tent heat solid iodine crystals
- Produces brown print (fades quickly!)
- For paper, cardboard, unpainted surfaces
What is the scientific name and function of Red Blood Cells?
- Erythrocytes
- They have hemoglobin and carry oxygen and carbon dioxide
- Hemoglobin is the iron-containing protein that gives blood its red colour
- They have no nucleus and no nuclear DNA
What is the scientific name and function of White Blood Cells?
- Leukocytes
- They are an immune system cell which fights disease and produces antibodies
- Only cells that contain DNA (only useful blood cells for DNA profiling)
What is the scientific name and function of Platelets?
- Thrombocytes
- Small cell fragments that assist in blood clotting and repair damaged blood vessels
Where is DNA found in blood?
Only cells that contain DNA are the white blood cells
How does one determine blood type?
Look for A and B antigens that are found on the surface of RBC’s
If a person has A proteins they have what blood type…
A
If a person has B proteins they have what blood type…
B
If a person has A and B proteins they have what blood type…
AB
If a person has neither blood proteins, they have what blood type…
O
How do you do determine a blood type
Perform an antigen test and look for agglutination if clumps, then has the protein
How are the blood groups broken down to create 8 different blood types?
Rh factor; if the antigen Rh is present the blood is Rh+ and if not the blood is Rh -
Why is AB blood unique
You can receive blood from a donor with any blood type (cells don’t make antibodies towards anything)
How is O blood unique?
- Can donate blood to anybody (universal donor)
- But can only receive from type O because cells make antibodies against both type A and B antigens
What is considered to be the universal receiver?
AB+
What is considered to be the universal donor?
O-
What is the most common blood type?
O+
What is the least common blood type?
AB-
What blood types can O+ donate to?
O+, A+, B+, AB+
What blood types can O+ receive from?
O+, O-
What blood types O- donate to?
All types (universal donor)
What blood types can O- receive from?
O-
What blood types can A+ donate to?
A+, AB+
What blood types can A+ receive from?
A-, A+, O+, O-
What blood types can A- donate to?
A+, A-, AB+, AB-
What blood types can A- receive from?
A-, O-
What blood types can B+ donate to?
B+, AB+
What can B+ receive from?
O+, O-, B+, B-
Who can B- donate to?
B-, B+, AB-, AB+
Who can B- receive from?
B-, O-
Who can AB+ donate to?
AB+
Who can AB+ receive from?
All types
Who can AB- donate to?
AB-, AB+
Who can AB- receive from?
AB-, O-, A-, B-
How do you test for blood at a crime scene?
- Look for presence using luminol or Kastle-Meyer
- See if it is human using ELISA test
- Then determine blood type by looking for the antigen proteins
What does luminol do/show?
- Luminol powder is mixed with hydrogen peroxide is able to detect hemoglobin left behind by blood
- Spray the area and if blood is present it will luminesce for about 30 seconds however it destroys the blood so it cannot be tested later
What is the Kastle-Meyer Test?
- Sawb turns pink if blood is detected
What is the ELISA test?
ELISA uses antibodies that react to human blood to tell if mammal blood is from human. ELISA stands for enzyme linked immunosorbent assay
What are presumptive blood tests
Test to see if there’s blood
- Kastle-Meyer and Luminol
What are confirmatory tests?
- ELISA
What are satellite droplets formed from?
Falls from height or high velocity
What does the tail of a blood drop entail?
Tail points in the direction of motion
What do the blood cells from mammals look like?
Mammals except camels and llamas have circular un-nucleated RBC’s
What do the blood cells of other animals look like?
Have oval blood cells with a nucleus
What is gel electrophoresis?
Smaller DNA molecules move faster than larger DNA molecules (shows lengths and placement of DNA bands)
Process:
- Restriction enzymes cleave DNA into smaller segments of various sizes
- DNA segments are loaded into wells in a porous gel. The gel floats in a buffer solution within a chamber between two electrodes
- When an electric current is passed through the chamber, DNA fragments move toward the positively- charged cathode
- Smaller DNA segments move faster and further than larger DNA segments
What is PCR?
- Polymerase Chain Reaction
- Is a technique that makes thousands of copies of segments of DNA
- Crime scene (template) DNA is mixed with nucleotides, an enzyme known as polymerase, and primers (base segments of complementary DNA that base-pair with the template DNA upstream of the region of interest and serve as recruitment sites for the polymerase
- Cycles of denaturation, annealing and extension are repeated to achieve exponential amplification of the target sequence
Where is DNA located in cells?
- DNA is a nucleic acid found in chromosomes, in the nucleus of your cells
- Chromosomes uncoil into DNA
What is the human genome?
- Is the total amount of DNA in a cell. It is contained in both the nucleus and mitochondria
- Human genome has about 3 billion base pairs
- Genome is to code the blueprint for the human body. It tells the body to make proteins and other molecules
What is complementary base pairing?
4 Nitrogenous bases
1. Adenine bonds with Thymine
2. Cytosine bonds with Guanine
DNA Database
- Named CODIS: Combined DNA Index System
- Each state keeps DNA profiles of individuals who have been convicted of certain kinds of crime
- Military maintains DNA profiles of all servicemen and women
What are the 5 types of stalking, and give a description of each…
- The Resentful Stalker: happens when they feel they have been mistreated or that they are the victim of humiliation or injustice, victims are strangers or acquaintances who are seen to have mistreated them, can arise out of mental illness
- The Rejected Stalker: begins after the breakdown of a close relationship, victims are usually former sexual partners; however, family members can also be targets; they attempt to get revenge or reconcile
- The Incompetent Suitor: stalks due to loneliness or lust and target strangers or acquaintances; they want to date or a short-term sexual relationship, they stalk for a brief period, but when they do persist their behaviour is maintained by the fact that they’re blind due to the distress of the victim
- The Intimacy Seeker Stalker: arises out of loneliness, victims are usually strangers or acquaintances who become the target for their desire, behaviour is fueled by mental illness involving delusional beliefs about the victim, such as the belief that they are in a relationship
- The Predatory Stalker: begins because of sexual interest, perps are usually male and victims are usually female strangers, stalking is way to obtain info
What are breech marks?
- Unique marks that are produced on the casing as it moves backward and hits the breechblock (prevents a cartridge from shooting backwards towards a user as it recoils)
What is Violent Crime?
Crimes against people
What type of crime is murder or assault
Violent
What is property crime?
Crimes against property (destroying)
What type of crime is vandalism?
Property
What type of crime is theft?
Property
What type of crime is bank robbery and arson?
Property
What is public order crime?
Contrary to moral values
What type of crime is peeing in public?
Public order
What type of crime is prostitution?
Public order
What type of crime is someone being drunk?
Public order
What is cybercrime?
Any crime committed via the use of the internet
What type of crime is identity theft?
Cybercrime
What type of crime is child pornography?
Cybercrime
What is white-collar crime?
Business related crimes
What type of crime is grand theft?
White collar
What type of crime is embezzlement?
White collar
What is organized crime?
Illegal acts committed by illegal organizations
What type of crime is sex trafficking?
Organized
What type of crime is drug dealings?
Organized
What type of crime is illegal gambling?
Organized
What type of crime is bribery/extortion?
On a major end, organized on a smaller end public order
What does a criminal profiler do?
Involves the investigation of a crime with the hope of identifying the offender, based on a crime scene forensics and analysis, investigative psychology, and behavioral science (they put together a potential offender description)
What information do they include in a profile for criminal profiling?
Psychological traits, mental illnesses, behavioural patterns, and demographic variables including age, race, and geographic location, crimes they have committed
How do criminal profilers develop their profile?
The facts and state of the crime scene. and forensic evidence found gives a basis
How are bullets named?
- They are named based on caliber and length
- Caliber refers to the diameter of the bullet, usually expressed in hundredths of an inch or I’m mm
- Caliber also matches the diameter of the inside of a firearms barrel
There are two ways that the term victimology can be used. Describe each…
- Studies how victims interact with the police
- Analyzes how and what some victims get chosen
(try to explain why some are more likely than others to become victims of a crime)
What is GSR?
- GSR is trace evidence made of smoke and unused powder particles that can land on the hand, arm, face, hair, and clothing of the shooter and victim
How does GSR help CSI’s?
The amount of GSR decreases as the distance between the firearm and the shooter increase, so it can be examined to help determine the distance between the victim and the shooter
What detects the presence of GSR?
Chemical tests (the modified Greiss test)
What are the 4 types of evidence search patterns?
Linear, Grid, quadrant/zone, spiral,
What are the different victim theories and give an example of each
The Precipitation Theory: suggests that some people’s actions/choices initiate or cause a particular confrontation that may lead to that person becoming victimized by injury or death (active occurs when the victim willingly puts themselves in situations using fighting words or threats and passive precipitation when the victim has characteristics that unknowingly motivates ie sexual assault)
The Lifestyle Theory: victims whose lifestyle increases criminal exposure are most likely to be victims ex. living in bigger cities, living alone, low income
The Deviant Place Theory: suggests that victims do not motivate crime, but rather are prone to becoming victims because they live in social areas that are disorganized and have high crime rates these places tend to be densely populated and impoverished/low income
The Routine Activities Theory: Three variable interactions that present the typical ‘routine activities of the traditional Canadian lifestyle
1. Available and suitable targets ie unlocked home
2. Lack of proper guardians ie caregivers, and police services
3. The existence of emboldened offenders such as addicts, young men, those who struggle with finances
