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ScT 11 – Forensics Review
Answer the following using your notes as needed.
1) Forensic science is the application of scientific disciplines to law. Before forensics was widely accepted,
criminals used to be convicted based mostly on eyewitnesses and confessions.
2) Key technologies that were important to the development of forensic science: microscopes, personal
cameras, bullet trajectory analysis techniques, blood typing techniques, DNA amplification techniques
3) The first forensics lab was set up in 1929 in response to the “St. Valentine’s Day Massacre.” The police
looked at shell casings found at the crime scene and compared them to those used in police weapons,
and to those used by weapons found in one of Al Capone’s hit men. The casings matched the hit man’s
gun, and cleared the police of the murders.
4) The true Crime Scene Investigators in Canada are highly trained police officers. These police officers are
usually called Identification Officers. Until recently Ident officers need at least 7 years’ service in the
police force, before entering the training period in Ident.
5) Physical transfer of materials such as hair, fibers, blood, and skin cells will occur whenever two people
come in contact with each other. Dr. Edmond Locard was the first to describe this principle of
exchange. The longer or more intense the contact between two people, the greater amount of trace
evidence present.
6) Evidence can be DIRECT. Statements of a witness in court would be direct evidence. Evidence can also
be INDIRECT or circumstantial evidence. Indirect evidence can either be physical evidence that might
be trace evidence or gross evidence, or it can be biological which includes blood, saliva, hair or fibers.
7) Any characteristics that are common to a group are called class characteristics. Characteristics that are
unique to a single person or item are individual characteristics.
8) A Canadian Crime Scene Investigation Team
Some specific forensic specialists include: Search Technologist - the RCMP officer responsible for
recovering all the different types of trace evidence that may be. Forensic Biologist - involves the
examination of evidence to recover DNA. Forensic Chemist - performs chemical analysis of materials.
This includes the analysis of fire debris for flammable liquids, Gun Shot Residue (GSR), paint, glass,
fibres, explosives, building materials and soil. Forensic Toxicologists concentrate on the chemicals
found in body fluids, primarily drugs, alcohol, and poisons and with chemicals related to the making
and using of drugs. Forensic document examiners try to answer questions about documents. Firearms
and Toolmark Examiners work involves the matching of the ‘toolmarks’ made on bullets and cartridge
cases upon firing. Coroner and Medical Examiners determine WHO died, WHERE did they die,
WHEN did they die, WHY did they die, HOW did they die. Forensic Odontologist are dentists with
added forensic training. Forensic Anthropologists are experts in human anatomy, specifically the
skeleton and of individual bones and teeth. Three jobs of a forensic artist: produce a near likeness of a
suspect based on a witness description, manipulation, enhancement and comparison of photographic
images, and perform techniques used to assist in the identification of human remains in various stages
of decomposition. Behavioral or Criminal Profiler analyze and interpret an offender's behavior as
exhibited through the crime/crime scene. A forensic botanist is a plant biologist who analyzes plant
evidence for legal cases. Forensic Entomologists study the insects associated with a human body or an
animal in order to estimate the time of death.
9 ) A primary crime scene is the place that the crime actually took place. A secondary crime scene is a
place related to the crime, but the crime did not occur there. A staged crime scene is a crime scene that
someone has altered to make it look like something it wasn’t.
10) The Seven S’s of Crime Scene Investigation 1) Securing the Scene, 2) Separate the witnesses, 3) Scan the
Scene 4) See the Scene (Photos of the overall area and close up photos with and without a measuring
ruler should be taken) 5) Sketching the Scene, 6) Search for Evidence 7) Securing and Collecting the
Evidence
11) Search Patterns include the following shapes: Spiral , Linear, Grid, Quadrant
12) Collecting evidence: Separate containers should be used for each piece of evidence. Gloves must be
worn. Label the outside of container with a minimum of collector’s name, date, time and description of
the evidence. Seal the container and place the collector’s initials and date on the seal.
13) Appropriate containers: Body Fluids – In porous container so that it dries and doesn’t rot. Glass or
other breakables - in rigid container. Metal Objects – in rigid container. Trace Evidence – in container
that allows no leakage so evidence isn’t lost by accident. Arson – in nonporous container to prevent lost
of evidence that might evaporate
14) An evidence log and a chain of custody must be attached to the evidence container. Evidence must
always be kept safely so that there’s NO chance any one could have changed it. Evidence is stored in an
“evidence locker” and is continuously guarded by a law enforcement officer. If someone unrecorded
handled the evidence, then the chain of custody is broken, and there’s a chance that the evidence may
have been altered.
15) There are grooves (valleys) and friction ridges (hills) on your fingers, palms, and soles of your feet.
The friction ridges are used to help you grip onto things. Every person has a unique pattern of friction
ridges that doesn’t change throughout their lifetime.
16) There are 3 main types of patterns to fingerprints: arches, loops and whorls. Loops are the most
common type of print, followed by whorls. The number of deltas can be used to determine if a print is
a loop, whorl or arch. A ridge count is a useful number, which you obtain by counting the number of
ridges from the center of the core to the edge of the delta. Fingerprints are usually matched by a
computer program called AFIS (Automated Fingerprint Identification System)
17) There are 3 main types of fingerprints made at crime scenes: plastic (3-D), patent (visible), and latent
(need something done to them to make them visible). To expose latent prints, you can brush powder
onto a latent print, and then lift it with tape and transfer it to a card. Before prints are lifted, they must
be photographed. You can also use chemicals to expose latent prints: iodine (fades quickly), ninhydrin
(purple, permanent stain), and superglue mixed with oven cleaner (make them 3-D and permanent).
18) Blood can be used in two ways as evidence during an investigation: to extract DNA for analysis or as
physical evidence when blood spatter is studied. Analysis of a splatter pattern can aid in determining
the direction blood traveled, angle of impact, point of origin of the blood, velocity of the blood, manner
of death.
19) When blood falls from a height or at a high velocity, it can overcome its natural cohesiveness and form
satellite droplets. When it falls onto a less-than-smooth surface, it can form spiking patterns around the
drops. When a drop of blood is longer than it is wide, it’s possible to determine the angle it was
traveling.
20) The location from which the blood originated (source) can be determined if there are at least two blood
spatters. Draw straight lines down the axis of the blood splatters. Where the lines converge, the blood
originated. This is called the point of origin.
21) Even after washing a room of visible blood, some blood evidence remains. A compound called
Luminol will cause hemoglobin to fluoresce under black light. Kastle-Meyer Test = if blood – dark pink
color is present. Leukomalachite Green = changes color to green in presence of blood!
21) Graphology: the study of what handwriting might mean about a person
22) Forgery is the illegal act of reproducing someone’s signature without their permission. The most
common type of forgery is when a person illegally signs another person’s name to a cheque to steal
money. Document examiners are handwriting experts who testify in court about the author of a
signature. Handwriting comparisons are useful because no two people have exactly the same
handwriting.
23) Handwriting samples can come from 2 sources: collected writing: writing that was done before the
investigation began and requested writing: in which an individual writes a dictated (spoken) text using
the same type of paper and ink that was used in the document in question
24) There are 12 basic characteristics used for comparing handwriting: Line quality, spacing between
words and letters, size consistency (is the ratio of height to width of the letters consistent), continuous
(is the writing continuous or does the writer lift the pen between words), are individual words
completely separate, cconnecting letters, letters complete (are letters completely formed), cursive and
printed letters (are there printed letters, cursive letters, or both), pen pressure (is pressure equal when
applied to upward and downward strokes), slant (do letters slant to the left, right or are they up and
down), line habits (is the text on the line, above the line, or below the line), fancy curls or loops (are
there unusual loops, curls or unique styles), placement of crosses on t’s and dots on i’s