Evidence and investigation • a. b. c. d.
Deductive reasoning Questioning Predicting Categorizing Inferring
• • •
Piecing together information Making connections Looking at the whole picture to problem solve
Deductive reasoning • Deductive reasoning involves piecing evidence together to make an educated assumption based on the clues present. • Nothing is assumed- it is backed up by clues
Common Vocabulary Suspect: person accused of a crime Victim: the person the crime is against Red herring: a false clue that is planted to throw off detectives Means: clues that show how a crime was done Motive: why a suspect does a crime Opportunity: the chance to do a crime Crime: something that is against the law
Types of clues • • • • • • • •
Tire prints Shoe prints Fingerprints Fibers Documents Soil samples DNA Impressions
Tire prints • Tires come in a variety of shapes patterns and sizes • By looking at a tire we can prove opportunity • Look for width,grooves and patterns Tires can tell Match the top with the bottom size of car Load type of car Direction of escape Speed of car
Shoe prints • Shoe prints can prove opportunity. • Even though there are many shoes alike we also look for wear to help tell similar shoes apart • Shoe prints can tell Direction suspect went Number of suspects Size of suspect Sex of suspect Activities of suspect Speed the suspect left the scene
Shoeprints:speed and direction Describe this scene
Normal stride Running stride
Fingerprints • Humans have known people have had different fingerprints for over 2500 years however only used by the FBI since1930 for crime investigation. • Every person has different fingerprints and they stay with us for life • Fingerprints can prove opportunity and help to link a suspect to means if fingerprints are on an object • Fingerprints are taken from a crime scene by LIFTING- Do lifting assignment
Fingerprints 2 • There are 4 main types • Whorl-Each round of circle on inside the other • Arch- rises on one side then comes back down but continues on • Loop/double loop- rises up and turns around and goes back to the original side • Composite -combo of the above or some thing that does not fit the others
Arch
Composite
Fingerprints 3
• These lines are made from raised skin called ridges and can be broken down into a smaller pieces • Ridge ending- ridge suddenly stops • Island- small ridge that stands alone • Lakes- small circular ridge • Bifurcation- forks off into two or more directions • Delta- triangle shaped
Fibers and Threads • Fibers and threads make up cloth • Different material are woven differently and can be traced back to a specific brand • Test for dyes thread pattern Flammability Wrinkle resistance Absorb water
Documents and Handwriting
• People who study handwriting are called graphologist • Every person has a distinct way of writing • Documents can prove motive • Graphologists look for
Spacing of letters and words Slants or letters or writing Pressure on page Formation of looped letters Dotted letters or crossed t How letters are joined Size of words style
Chromatography • Certain inks and dyes are made by mixing other colours. • When chemicals are mixed, the dyes run and the colours are released. The pattern of colours can be
Soil • Soil can be a great place for clues. It can tell: Direction Footprints All soils are different so it can tell place Number of people Something dragged
Crime Science Clue type 7 Impressions and markings
Impressions • • • • •
Impressions can prove means -how some one entered a place -how some one killed some one Impressions can prove opportunity Placing some one at the scene of a crime (teeth impressions in gum)
Markings • Knives and bullets can leave marks in objects that can be linked back to a specific knife or even gun • Ballistics is the study of these markings on a bullet left by the barrel of a gun
Clue type 8 DNA
• DNA is called deoxyribonucleic acid • It is the building blocks for life we all have DNA and each person’s is specific to them and only them. • DNA can prove opportunity placing someone at the scene of a crime • DNA is studied doing chemical tests and xrays. They then do overlays like fingerprinting
Where can they get D.N.A.? • D.N.A. is all over us. It is like “the legos” to build you and you leave pieces everywhere you go. • Examples Spit Skin
Hair
Blood
Fingernails