1. The Crime Scene

2. 3 methods for crime scene recording:
Record The Scene
Records of the crime scene in its original state will be used in the subsequent investigation, as well as at trial if necessary.
3 methods for crime scene recording:
Photography
Sketches
Notes
Ideally, all three should be used but photography is not always available so sketching and notes should be done at the very minimum.

3. Photographing the Scene
The prerequisite for photographing a crime scene is for it to be unaltered.
If objects are moved, positions changed, etc. before the scene is photographed, it must be documented in the notes.
At a minimum, 4 types of photographs are required:
Overview photograph-shows the entire area and all adjacent areas where important acts occurred before or after the crime.
Medium-Range photographs-photographs of objects in relation to the rest of the scene.
Close-Up photographs-used to record the details of the object.
Close-Up photographs with a scale-a ruler is placed in the photograph to show the relative size of the object.

4. Sketches Done after the photographs have been taken. 2 Types:
Rough Sketch
Finished Sketch
Sketches should include:
All objects that are part of the scene
Dimensions of the area and objects of interest
A key to show what the objects are
A compass
Neat and detailed
Scaled appropriately

5. Rough Sketch
Finished Sketch

6. Notes Note taking must be constant and must include:
A detailed written description of the scene
Location of items of physical evidence recovered
Time an item was discovered
Who it was discovered by
How and by whom it was packaged and marked
Who took the item from the scene
Remember that this record must be sufficiently detailed because it might be the only source of information for refreshing one’s memory weeks, months or even years down the road.
Audio recordings are a faster way to take notes at the scene, however, they have to be transcribed into a written document soon after their recording.

7. Search methods

8. Types of Memory

9. Fingerprinting

10. No two prints are alike-can be used as identification
3 Principles
No two prints are alike-can be used as identification
A fingerprint will remain unchanged during an individuals lifetime.
Fingerprints can be classified into three ridge patterns.

11. Types of Prints
Visible: prints made after coming into contact with a colored material.
Plastic prints: ridge impressions left on a soft surface such as wax.
Latent prints: ridge impressions caused by the transfer of sweat and oils on the skin. These must be developed!

12. Loops: enter, loop around, and exit the same side
Ridge Patterns
Loops: enter, loop around, and exit the same side
Radial and Ulnar
Whorl: circle pattern that has one core and one delta
Plain whorl, Central Pocket Loop, Double Loop
Arch: enter on one side and exit the other side
Plain Arch, Tented Arch

14. Francis Galton: classified prints into loops, whorls, and arches
Important People
Alphonse Bertillon: first system of classification based off measurements and photographs.
Henry Fauld: first person to suggest using fingerprints as identification. Proved in the first court case.
Francis Galton: classified prints into loops, whorls, and arches
Dr. Juan Vucetich: created the first classification system that allowed prints to be filed and recalled when needed.

15. AFIS
A database of fingerprints used to identify a print
To make a match: characteristics must be identical and have the same relative location to one another.
Most judicial systems accept between 8 to 16 points to conclude that it’s the same print.

16. Hair and Fibers

17. Hair

18. Used to determine if the hair was pulled out or fell out.
Structure
3 Parts:
Follicle
Used to determine if the hair was pulled out or fell out.
Root
Shaft: used to determine if the hair is human or animal.

19. Shaft
3 Layers:
Cuticle: outer covering in 3 scale structures: imbricate, spinous, and corona.
Cortex: middle layer that includes the pigment molecules
Medulla: inner layer that is made up of cells.
The medulla is used to determine if the hair is human or animal. If the medulla is greater than 1/3, it is most likely an animal hair.

20. Fibers

21. Types of Fibers Natural: plant, animal, and mineral sources.
Variation is shape
Most common is cotton
Synthetic: manufactured from petroleum, coal, or other synthetic chemicals
Uniform in shape
Most common is polyester

22. Plain: yarn goes over and under each strand.
Weave Patterns
Plain: yarn goes over and under each strand.
Resembles a checkerboard
Twill: one yarn goes over 3 before going under.
Creates a stair-step pattern
Satin: one yarn goes over 4 or more before going under.
Creates a pattern that looks like bricks
Knitted: interlocking loops

23. Can be used to analyze the type of dye and therefore the manufacturer.
Chromatography
Used to separate dyes
Can be used to analyze the type of dye and therefore the manufacturer.

24. DNA Analysis

25. Structure of DNA
Double Helix made up of nucleotides: Adenine, Thymine, Guanine, and Cytosine
Complementary base pairing: A binds to T and C binds to G.
Polar: goes from 5’ to 3’ and the opposite direction in the other strand
8% of our genetics code for our traits, the rest are switches, and further instructions
Mitochondrial DNA: found in the mitochondria and comes from our mothers.
Much more common than nuclear DNA and can be used as an alternative when nuclear DNA cannot be found or there is not enough

26. Collecting Biological Material
Proper Clothing:
Latex or Nitrile Gloves
Face mask
Boot covers
Eye protection
Lab coat/coveralls
Photograph and documentation (sketches and notes)
A substrate control: a piece of the material that is close but not part of the biological material being collected. Used for a comparison.

27. Collecting Biological Material
Biological materials should be placed in a paper bag or well ventilated box to discourage the growth of bacteria
Dried blood is swabbed with a Qtip that has been dipped in distilled water. The Qtip then goes into a well ventilated box for transport.
Soil that contains blood is packaged in an airtight container and immediately frozen. This is to discourage the growth of bacteria that is naturally in the soil.

28. RFLP

29. Restriction Fragment Length Polymorphisms
11 Restriction Enzymes are used to “cut” the strand of DNA at a specific nucleotide sequence created fragments of different lengths.
We use gel electrophoresis to separate the strands of DNA
Fragments travel from the negative to positive electrode
Smaller fragments travel farther than large fragments
Creates a ladder
Original Method of DNA Analysis
Requires a large sample of DNA
Subject to degredation

30. PCR and STR’s

31. PCR-Polymerase Chain Reaction
A method of making many copies of a piece of DNA by cycling through heating and cooling to artificially replicate DNA.
Strands of DNA are separated
Enzymes add nucleotides starting at the primer sequence
Makes about 1 Billion Copies in 3 hours

32. STR-short Tandem Repeats
Looking for a repeating sequence of nucleotides at 13 specific locations on both chromosomes.
The number of repeats will differ in each individual so we can use them to identify a suspect.
The STR’s are separated by length using gel electrophoresis.
New Method of DNA Analysis
Requires a much smaller DNA sample
Is not affected as much by degradation