1. Science of Crime Scenes
Chapter 6.4
Science of Crime Scenes

2. Other types of evidence
Science of Crime Scenes

3. Other types of evidence
Because anything can be evidence, sometimes it is difficult to characterize or classify an item as a piece of evidence
Some evidence is both the substrate and the trace
for example, like a questioned document
other types are means to a criminal act
like a cellphone
Evidence can be both biological and physical (like diatoms), or even be living (as with insects) or the by-products of life (like odors).
Science of Crime Scenes

4. Science of Crime Scenes
Questioned documents
Forgery
Counterfeiting
Handwriting analysis
Printed materials identification
Document dating
Document security
Ink analysis
Paper analysis
Science of Crime Scenes

5. Science of Crime Scenes
Questioned documents
As technology increases, so does the number and complexity of documents
For example
Credit cards
Drivers licenses
Passports
Documents can be intrinsically proofs in themselves, but also substrates on which other evidence is found, like DNA or fingerprints
Science of Crime Scenes

6. Evidence and substrate
even a single document can be exposed to numerous types of analysis or examination
focus not only on the document material itself, but also on all the materials constituting the evidence:
Staples
Tape
Clips
Paper
Printer or copier samples
Pens, inks, and other related materials
Science of Crime Scenes

7. Computers, cellphones, storage devices
Classical devices containing digital data
Computers
external disk drives
compact discs (CD/DVD/Blu-ray)
universal serial bus (USB) flash drives
memory cards
DAT bands
Science of Crime Scenes

8. Computers, cellphones, storage devices
Digital data are also stored on
mobile phones
smart phones
subscriber identity module (SIM) cards
smart cards (bank and credit cards, identification cards, season tickets, etc.)
global positioning service (GPS) units
portable media players/computers (iPods, iPads, and the like)
Science of Crime Scenes

9. Science of Crime Scenes
Digital crime scene
collection process is divided into two phases:
system preservation: aims to preserve the state of the digital crime scene, to reduce the amount of evidence that may be lost (volatile or overwritten)
evidence collection: Once the live data are secured, the system can be turned off for a “dead” analysis
Science of Crime Scenes

10. Science of Crime Scenes
Pollen
Palynology is the study of the reproductive grains and spores of plants (pollen)
Pollen is specific to each type of plant and the grains themselves are very resistant to damage
The mixture of various pollens and spores characterizes a pollen batch, which has the ability to infer an environmental area
Palynology can also be used with success to link illicit plant material specimens or samples
Collect the whole substrate (carefully) or swab the objects with distilled water and retaining the swab as well as the item
Science of Crime Scenes

11. Science of Crime Scenes
Bones
Skeletal material on the surface should be flagged and collected systematically
buried remains should be excavated using basic archaeological techniques
The ground should be cleared of all vegetation, the grave delineated, and the “work zone” kept clear of all personnel except those excavating
All recovered soil should be sieved during excavation to help collect small pieces of bones or evidence, such as bullets
Photographs should document all of the steps and the whole uncovered body
Science of Crime Scenes

12. Insects and Time since Death
Minutes after death, blow flies arrive to lay eggs or live young (larvae; singular larva) in the dead flesh that will nurture them
Waves of insect activity assist and accelerate the decomposition process
Necrophagous insects are followed by insect predators and opportunistic species, some of them carnivorous
Their life spans that allow forensic entomologists to determine how long a body has been exposed to insects present
Science of Crime Scenes

13. Science of Crime Scenes
Forensic entomology
Collecting both maggots (juvenile insects) from and around the body and the remnants of their development (small, hard cases called pupae) allow the entomologists to infer the sequence of insects up to the first arrival
Other available information an entomologist might be able to provide would include the time of year a species is more active, if the body has been moved, or species that are notably absent, which might indicate attempts to obscure a crime
Science of Crime Scenes

14. Science of Crime Scenes
Diatoms
Diatoms are microscopic unicellular algae that have a silica shell that is resistant to acids, heat, or body decomposition
They live in colonies, grow in abundance in fresh and salt waters, and their “skeletons” are widespread in soils
Diatoms can be used to determine a lethal drowning:
A massive inhalation of water introduces the diatoms into the lungs and they break through the thin walls of the lungs and move to deeper organs through the bloodstream
Diatoms vary within a few kilometers and over seasons; highly specific
Science of Crime Scenes

15. Science of Crime Scenes