Term 4 Forensics Test Flashcards
what is locard’s exchange principle?
every contact leaves a trace
what does forensics mean?
connected to or used in courts of law
what is a disadvantage of collecting samples for comparison?
the sample is only helpful if you have something to compare it to (e.g. a suspect’s blood)
what are the 3 main areas involved with forensic science work?
field science, medicine, and laboratory science
what is field science?
crime scene investigation (fire and explosion scenes, illegal drug labs, etc.)
what areas may be involved in field science?
- security of the crime scene
- preventing contamination
- locating and collecting evidence
- interpretation of evidence
- possible reconstruction of the event
what jobs are included in medical science?
forensic pathology, forensic medicine, forensic psychiatry and psychology, forensic odontology, and forensic anthropology
what is forensic pathology?
post mortem examinations of reported deaths (e.g. sudden/unexpected deaths, accidents, injuries, possible homicides, etc.). conclusions are then made about the cause of death
what is clinical forensic medicine?
examining victims of crime and suspects which have sustained injuries whilst committing a crime. interpretations are given about the possible causes and timing of injuries
what is forensic psychiatry and psychology?
the mental state of a suspect or victim during a crime and/or their fitness for trial
what is forensic odontology?
identifying bodies or skeletal remains from dental records, recontructing faces, and interpreting bite marks
what is forensic anthropology?
knowledge of human anatomy, which assists identification of skeletal remains
what does laboratory science include?
chemistry, biology, toxicology, ballistics, fingerprints, questioned documents, marks and impressions
what jobs are included in laboratory science?
forensic chemist and forensic biologist
what is a forensic chemist?
can have many varied roles, such as detecting and identifying illicit drugs, accelerants (arson), explosives, and gunshot residues, and trace evidences (e.g. paint, glass, fibres)
what is a forensic biologist?
primarily works on DNA profiling, where it is possible to match DNA from a scene exactly to a suspect (samples used include blood, saliva, semen, and hair)
what is toxicology?
the detection and identification of illicit and pharmaceutical drugs and poisons, interpreting toxicity levels and the effects on the functions of the body
what is ballistics?
the study of firearms and ammunition, and the identificaion of particular guns used from fired cartridge cases and projectiles. it can determine the angle and distance a gun was fired from
what is forensic entomology?
the application and study of insect biology to criminal matters.
what are the uses for forensic entomology?
while it is usually used to determine the time of death for a body, forensic entomology can also be used to detect drugs and poisons, determine the location of an incident, and find the presence and time of the infliction of wounds
how does forensic entomology help to determine the time of death for a body?
due to their extremely regular life cycles, forensic entomologists can use the insect samples on the body to track backwards and determine when the insects first began breeding. this can predict the time of death to a high level of accuracy
what is forensic serology?
primarily responsible for the detection and identification of biological material (e.g. blood, semen, saliva, urine) on physical evidence
what does fingerprint science involve?
the detection of fingerprints on a range of different surfaces, using a variety of techniques, in order to identify fingerprints and link suspects to crime scenes
what is the discipline of questioned documents?
incorporates examination and identification of handwriting impressions and machine generated documents (type writers, printers, etc.) to determine the origin of the materials (paper, ink)
what can leave marks and impressions at scenes?
implements such as bars and screwdrivers, shoe soles, and vehicle tyres
what other areas may be involved in forensic sciences depending on the circumstances?
- botany (plants)
- linguistics (language)
- engineering
- microscopy (trace evidences such as hair and fibre comparisons, or ballistics)
what kinds of documents can be forged?
banknotes, licenses, passports, or credit cards
what are some ways that you can tell if handwriting has been forged?
- the dots on the i’s and j’s are different
- the pressure of the pen is different
- the angle or slant of the writing is different
- the loops in the writing are different
- the size of the writing is different
what is chromatography?
a process used to separate mixtures by moving them through another substance (e.g. paper)
how does chromatography work?
the chemicals in a mixture are attracted to the paper differently. chemicals that are attracted to the paper strongly do not move far, whereas those that are attracted to the paper weakly move the greatest distance, therefore separating the components
what are some examples of solvents that can be used to help colours climb up the paper in paper chromatography?
water and methylated spirits
what is the core body temperature of a healthy, living human?
37 C
what is the rate of cooling for a dead body?
0.8 C every hour until is reaches room temperature
how long does it usually take for a body to cool?
within a day, although the exact conditions, such as weather and clothing, can speed up/slow down the process
what are some changes that occur in a body after death?
- skin pales
- muscles gradually get stiffer
- later on, muscles relax again and the skin discolours as the body begins to decompose
- the skin takes on a greenish appearance within 2 days of death as bacteria begin to decomopse the body
what is rigor mortis?
the condition where the muscles stiffen in a dead body
what is livor mortis?
the condition where the skin of a dead body turns a purplish-blue colour
what is pallor mortis?
the condition where the skin of a newly dead body turns pale
under what circumstances will the coroner instruct that an autopsy be performed on a dead body?
if there is doubt about the identity of the corpse oe the way that the person died
what is an autopsy?
a systematic dissection of a corpse
who performs an autopsy?
a pathologist (a doctor who specialises in the study and diagnosis of diseases)
what is the first step of an autopsy?
the body is inspected, and external marks and injuries help the pathologist determine what to do next
what happens in an autopsy if the pathologist determines that the death was natural?
a long cut is made along the body, and the internal organs are removed to determine the cause of death
what happens in an autopsy if the pathologist determines that the death was suspicious?
- a cut in the shape of a T or a Y is made on the chest, and the ribs are cut, allowing the organs to be examined while still in place
- the organs are removed and body fluids are collected for later testing
- the top of the skull is cut and the brain is removed for dissection
what are biometrics?
the identification of people based on their characteristics or traits
how can biometrics help identify a living person?
we can observe their behavioural traits, such as their gait (style of walking) or their voice
how can biometrics help identify a dead person?
we can measure physiological traits, such as fingerprinting, face recognition, and iris recognition
why is fingerprinting such a widely used method for identifying people?
because no 2 people have the same fingerprint
when do fingerprints form on a person?
in the womb, between the 4th and 5th months of pregnancy
where are fingerprints located on a person?
fingers, palms, and soles of their feet
what is another name for fingerprints?
friction ridges
what are the 4 types of fingerprint patterns?
loops, whorls, arches, and composite
what are the 2 glands below the layer of epithelial cells on the surface of our skin?
sweat and sebaceous glands
what do sweat glands release?
sweat, which contains water, salt, and urea
what do sebaceous glands release?
oils
how are fingerprints created?
when we touch a surface, we leave behind a print of oils and sweat. when police dust for prints, the dust clings to the fluids to expose the print
what are the 2 types of fingerprints that can be collected?
visible and latent prints
what are visible prints?
visible prints are formed when the finger is pushed into a soft surface (e.g. putty, clay, gum, blood, mud, etc.) and leaves a visible mark (without dusting)
what are latent prints?
latent prints are formed when oils and sweat leave an invisible print on a surface
what is a non-porous surface?
a surface that is hard and shiny, e.g. metal, marble
what is a porous surface?
a surface that is absorbant e.g. paper, fabric
how do you collect latent prints on a non-porous surface?
using a dusting method with powder and sticky tape
how do you collect latent prints on a porous surface?
using the iodine gas method, or a nihydrin solution
what are different sections of chromosomes called?
genes
what are genes made up of?
DNA
what is DNA short for?
deoxyribonucleic acid
what cells is DNA found in?
the nucleus of every cell in your body, except for red blood cells
why can we use DNA to identify a person?
because everyone’s DNA is unique, unless you’re an identical twin
what does DNA control?
the production of proteins in the cell
what do proteins do?
they form all the structural parts of a cell, and they control all the chemical processes
what does DNA look like?
it’s made up of 2 long strands that twist around each other to form a spiral structure called a double helix
how are the 2 long strands of DNA bonded together?
with pairs of nitrogen-rich bases in the middle
what are the sides of DNA made up of?
alternating phosphate groups and deoxyribose (sugar) molecules
what are the 4 bases that help make up DNA?
adenine, thymine, guanine, and cytosine
which bases pair together?
adenine and thymine pair, and guanine and cytosine pair
what is DNA profiling?
examining the DNA from a crime scene (human biological fluids such as blood, semen, or saliva) and comparing it to other samples
what could DNA from a crime scene be compared to?
a suspect’s DNA, samples of DNA on a database, relatives’ DNA, or victim’s DNA
what technique is used to create multiple copies of DNA found at crime scenes?
polymerase chain reaction (PCR)
what process is used to sort DNA?
gel electrophoresis
what does DNA tell us?
that a suspect was at a crime scene at some time
what doesn’t DNA tell us?
when a suspect was at a crime scene or why they were there
how can teeth help to identify a body?
- people have distinctive dental records, as no 2 people have the exact same teeth or dental procedure history
- bones (including teeth) take a long time to decompose, so you’re able to use them as evidence for a long time
how can teeth help to identify a body?
- people have distinctive dental records, as no 2 people have the exact same teeth or dental procedure history
- bones (including teeth) take a long time to decompose, so you’re able to use them as evidence for a long time
what are some ways to identify/differentiate skeletons?
- badly broken bones will have pins, plates, and screws inserted
- some people may have replacement knees or hips
- teeth grow until the age of 20 (this can help determine the age of the corpse)
- jewellry, beltt buckles, and buttons left on the skeleton can also give an idea of the gender and age
- age and gender of a corpse can be determined by the size and density of large bones such as the pelvis, skull, and femur
what are 3 ways to identify a body?
- DNA analysis
- fingerprinting
- marks such as tattoos and birthmarks
what are some accurate forensic evidence types?
- DNA testing from a single person
- fingerprint analysis
what are some semi-accurate/in doubt forensic evidence types?
- firearms analysis
- DNA testing from different people
- footprint analysis
- hair comparison
what is a non-accurate forensic evidence type?
- bite mark comparison
what does the size and shape of a blood spatter tell us?
the height and direction that the blood fell from
how can you reveal blood that has been wiped or washed from a surface?
using UV light
what are the 3 types of blood spatters?
directional, drip stain, and flow pattern
what is a directional blood spatter?
elongated drips that indicate the direction the blood was moving when it hit a horixontal surface
what is a drip stain blood spatter?
circles that indicate that the blood dropped vertically from a short distance
what is a flow pattern blood spatter?
indicate the direction the blood was moving when it hit a vertical surface
what is used to detect unseen blood?
luminol
what protein molecules dictate the differences in human blood?
antigens and antibodies
where are antigens located?
on the surface of red blood cells
where are antibodies located?
in the blood plasma
