FORB201 - Class Test
How do we increase penetration of a bullet?
Higher penetration is caused by a higher momentum. Therefore increase mass or increase velocity!
Gauge is ...?
How many rounds you can make with one pound of lead to fit in your gun
What are the 5 Major Questions at the Crime Scene?
Who? Were the victim, perpetrator, witnesses What? Was the sequence of events (method of operation) When? Chronology of events Where? Location of crime Why? What was the motive of the crime
Other reasons for studying ballistics?
In the military setting, commercial aspects (e.g. hunting) and injury prevention and protection
How does the Phadebas Test work?
Reacts with alpha amylase to release a blue dye
How do we analyse trace evidence?
Recover and compare to a known factor
What is the cavitation effect?
Where small and large empty cavities are generated in a fluid, which initially expands to a large size then rapidly collapses.
Apart from increasing mass or velocity, what are some of the other ways to increase penetration?
- Hard tipped bullets -Piercing point on missile -Small point of entry followed by large mass (stiletto effect)
What are some of the differences between DVI and Criminal Forensics?
- Victim of a crime vs. accidental death/suicide -Coronial Court vs. Criminal court -Circumstances of death vs. guilty or innocent?
What are the steps in gathering biological evidence? (4)
1) Gather information surrounding the case 2) Formulate forensic strategy - what questions do you want to answer? Why are you collecting the sample? 3) Photograph and document the scene of the crime 4) Begin forensic examination - visual search, screening and presumptive testing of stains.
What is the criminal investigation process if the killer disappears/a body is found?
1) SOCO comes - investigates dead body 2) Detective attends 3) Environmental Science and Research (ESR) who have leading forensic experts attend and collect evidence 4) Coroner, Pathologists attend.
What is the function of a Forensic Scientist?
1) To ANALYSE physical evidence - identify and recover from a crime scene 2) To act as an EXPERT WITNESS whose skills and knowledge will aid a decision in court
What is a plastic/fibre composite?
80% Fibre embedded in a stiff plastic capsule.
What is a ballistic body?
A body which is free to move, behave and be modified, which is influenced by ambient environmental conditions, substances or forces such as gravity, air particles and pressure of gases in a gun/
What was Leone Lattes known for?
ABO Blood Typing
What do the disciplines of forensic science do?
Answer questions posed by the legal system
What are some examples of people who call themselves a forensic scientist?
Anthropologist, Chemist, Entomologist, Pharmacist, Dentist, Artist
What was Alphonse Bertillion known for?
Anthropometry (Size, weight and proportions of the human body)
What is Forensic Biological Evidence?
Any cells or body fluid containing DNA which can be used for identification purposes
What is forensic odontology?
Application of dentistry to the field of law.
What is the role of the first attending officer?
Assesses the scene and determines level of assistance required Initally in charge of the scene
What was Calvin Goddard known for?
Ballistics
What is a famous case of Locards Principal?
Ben Smart and Olivia Hope - hair was found on boat
What is a controversial area of forensic odontology?
Bite Mark analysis
What are some forensic odontology techniques used?
Bite Mark analysis Maxillofacial trauma (e.g. GSW) Age estimation Teeth found at the crime scene (ID of unknown remains)
What types of cases is the Phadebas test often used for?
Bitemarks, sexual attacks and child abuse
What is biological shrapnel?
Bits of organism e.g. dog femur in the abdominal cavity
What else does luminol react to?
Bleach, Copper, Horseradish
What does the Kastle Meyer test test for?
Blood - hemoglobin
What does luminol test for?
Blood - reacts with iron in Hb causing luminescent stains
What are some of the different ways biological evidence can be collected?
Blood - swab Saliva - Swab Cigarette Butt- entire item Clothing - swab or item
What filter do we use for hair?
Blue light
What filter do we use for semen?
Blue light (425nm)
What are some false positives for the Kastle Meyer Test?
Broccoli and cauliflower (other oxidising agents)
What can cause ballistic injuries?
Bullets Fragments Secondary Missiles Biological Shrapnel
What does the cavitation effect cause?
Bursting of surrounding organs causing further internal damage. This is caused by changes in hydrostatic pressure.
What is a problem with the acid phosphatase test?
Can destroy DNA if entire item is used, so use a swab
What use does Locards Principal have?
Can link suspect to the scene of the crime.
What is the role of the SOCO?
Collects physical evidence Coordinates with forensic scientists.
What causes trace evidence?
Contact between two surfaces
What is 'the standard' of forensic individualisation techniques?
DNA - it is reliable, and if not fraudulent the probabilities of a false positive are rare! Mistakes are not common.
What are three primary human identification techniques?
DNA, fingerprints and odontology
What is the criminal investigation process if a killer calls the police?
Detective looks at physical, psychological and forensic relationship to find a motive and/or evidence SOCO collects forensic evidence.
What was Albert S. Osborn known for?
Document Examination
Who were the 'Fathers of Forensics'?
Edmund Locard - The Locard Principal 'Every contact leaves a trace' Conan Doyle - Wrote Sherlock Holmes which inspired Forensic Investigation
What is kinetic energy?
Energy converted into motion
Perforating is ...?
Entry and exit wound
Penetration is...?
Entry wound
A Glaser round is ...?
Filled with ball bearings
How does the hand held intensity light source work?
Filters are used to change the wavelength, which allows for specific forensic evidence to be targeted
What was Francis Galton known for?
Fingerprint classification
What are some examples of trace evidence?
Fingerprints, footprints, hair follicles, pollen
What did Mathieu Orfila found?
Forensic Toxicology
Jacketing of bullets prevents ....?
Fragmentation - its more humanitarian
What is a secondary missile?
Further injury from a hard structure such as teeth or bone, as they move through the soft tissue and damage internal organs - potentially more damage than initial projectile
What is the rifling effect?
Grooves in barrel mean the projectile is spiralled which enhances accuracy
Rifling is ...?
Grooves inside the barrel
What do we use to screen for biological evidence?
Hand held high intensity light source
What is ceramic faced armour?
Hard ceramic plates (brittle) break up the missile first, then the composite material dissapates the energy before reaching the body.
Why should we study ballistics in regards to injuries?
Important in ballistic injuries e.g. understanding the mechansim of injury, energy, entry and exit and how wound is produced
What is Forensic Biological Evidence used for?
Identify Offender Link a suspect to a victim Put a person at the scene of the crime Reconstruct a sequence of events
What is the mechanism which causes a modern bullet to be fired from a gun?
Ignition sparked, sets off propellant gas which releases the bullet
What filter do we use for blood?
Infared
Why do we have to be cautious before removing biological evidence from the scene?
It essentially ruins it
What are some examples of high performance fibres?
Kevlar, Nylon, PBO
What are the relative proportions of calibre to propellant in low velocity rounds?
Large calibre to amount of propellant
What effect do low velocity rounds have?
Local bruising at entry point Penetrate Low level cavitation effect (core and trap inside body)
What is forensic science?
Method of gathering and examining information about the past which is used in the court of law.
Name some types of 'Volume' Crime
Minor Arson, Assult (affray), Robbery, Burgulary, Theft of a Vehicle
What is Trace Evidence?
Minute traces of evidence usually invisible to the naked eye
Avulsive is ...?
Pulled off or torn away e.g. arm blown off
Name some types of Major Incident Crime
Murder, Attempted Murder, Rape, Kidnapping, Drug Factory
Notching on bullet causes?
Mushrooming
What is a limitation of high performance fibres?
Not stab proof
What is a limitation of luminol?
Only works in the dark
What is the role of the Investigating Officer?
Oversees and Coordinates what happens at the scene Takes charge of scene Liason with all parties (SOCO and 1st attending)
A higher momentum means a higher ............. ?
Penetration
What effect do high velocity rounds have?
Perforate (in and out) Cause high levels of cavitation Stress wave caused due to high velocity High energy transfer levels
How does the Kastle Meyer test work?
Phth is used Stain is swabbed, ethanol added to swab, Phth added and if it turns pink - positive result!
What disciplines does forensic science include? (4)
Physiological Science - e.g Pathology, Biology, Chemistry, DNA Profiling Digital Forensics e.g. Computer, Audio, Video Forensic Criminalistics - e.g. Ballistics, Textiles, Toxicology, Fingerprints Social Sciences - e.g. psychology, psychiatry
What types of guns are low velocity?
Pistol or handguns
How does a plastic/fibre composite work?
Plastic shatters with bullet and dissapates energy superficially, weave underneath can now deform.
What causes the cavitation effect?
Pressure wave from the energy expended when the bullet moves through the body - need the material to be a fluid!
What does the Phadebas test test for?
Presumptive test for Saliva - the enzyme alpha amylase (may be present)
What types of guns are high velocity?
Rifles
What are non lethal rounds?
Rubber or plastic, causing significant soft tissue damage.
What is the acid Phospatase test used to detect?
Semen - ACP is in high concentrations.
What are some examples of Forensic Biological Evidence?
Semen, Blood, Saliva, Trace (sweat or touch), Teeth, Bone, Nasal secretions, Hair with root attached
What are some examples of things the hand held high intensity light source is used to detect?
Semen, blood, saliva, bone, teeth, hair, fingerprints, gunshot residue and accellerants
Calibre is ... ?
Size of the projectile/diameter
What are the proportions of high velocity rounds?
Small calibre to large amount of propellant
Why study ballistics in the forensic setting?
So we can study mechanisms of injury, trajectories (i.e. where killer shot from) types of weapons used for crime and seeing if the evidence fits the story!
How does the acid phosphatase test work?
Suspect stain is swabbed and a phosphate and fast blue B is added. Turns blue/purple if positive. Can destroy DNA
What is Locards Principal?
That the perpetrator will bring something to the crime scene and leave with something from it.
How do high performance fibres work?
The dense material is Woven - so force of projectile is dissapated across the weave
What is Ballistics?
The motion, behavior and effects of projectiles
Why are ballistic principals used in weapons development?
To develop and design projectiles such as bullets, missiles, mines, fragments etc. to achieve a desired performance
What is more efficient, increasing mass or velocity?
Velocity as Ek=1/2 mv^2, so velocity quadruples the Ek if increased by double.
Why is prints not as reliable as DNA?
We need futher research into sources of error of friction ridge ID. Like is the uniqueness of prints worth using - due to error rates
What are some of the movements which happen despite the rifling effect?
Yaw, Tumbling, Precission, nutation
