Lecture 2: Deep Dive into Trace Evidence Flashcards
What is inceptive evidence?
Evidence which shows whether or not a crime has been committed.
What is identification evidence?
- It identifies the owner
- E.g fingerprints/marks & DNA
What is associative evidence?
Has contact occurred?
What considerations need to be taken into account for trace evidence?
- The strength of evidence is determined by case context and material ‘uniqueness’
- There’s always a two way transfer but one of the transfer may be more obvious than others, i.e additions to the scene may be easier to spot than things removed.
- Non-contact and 1⁰, 2⁰, 3⁰, etc contact can happen.
- Absence of evidence doesn’t mean evidence of absence.
- Associative evidence may not mean contact has occurred.
Why shouldn’t you say something is unique?
- Never actually say something is unique as you would have to definitively know that there is nothing else like it
- Statistically, you can’t say something is ‘unique’.
- Use the term characteristic not unique
What are some transfer conditions?
- Substrate/type of material found on and the type itself
- Temperature - things adhere more if you’re sweating
- The friction involved / pressure
- More surface area in contact between material and substrate = more is transferred
- Length of time of contact
- Environmental factors
- Shedding - Wool is more likely to shed
- Nature of contact
- Frequency - If you’re hit one you’ll have less trace deposited on you than if you were hit multiple times.
Persistence of evidence considerations
- The temperature of the environment
- Contamination
- Evidence tampering
- Exposure to elements
- Emergency personnel
- Nature of material
- Substrate
- Nature of contact
- Contamination
- Post-deposition activity
- Cleaning/laundering
- Environment/weathering
- Animals
- Trace embedding
Crime –> Recovery time, Recovery time –> analysis time
What are the challenges to trace evidence?
- Efforts of emergency personnel
- Scene tampering
- Not detected
- Detected but value not recognised
- Detected and recognised but not relevant to case
- Overwhelming amount of trace – anything can be evidence
- Inappropriate collection technique – loss/damage
- Inappropriate storage – loss/degradation
- Inaccurate interpretation
What are some recovery of evidence considerations?
- Recover trace or entire item?
- Gloved hand or tweezers?
- Wet samples?
- Gelatine lifters
- Sequential vs. zonal tape lifting
- Vacuum sweeping
- Swabbing
- Control samples
How can gelatin lifters be helpful?
- Black so it’s easier to visualise.
- Primarily created to lift prints so you don’t have to develop them.
- It’s tactile so it will pick up the trace evidence better.
What are some drawbacks to gelatin lifters?
- As it’s gelatin it’s made of collagen so you need to be careful you don’t lift anything with DNA as it will affect DNA.
- Makeup contains collagen so can’t use it to lift makeup
How can ESLA be useful?
Not for footwear marks!
The dust and other materials that make up the footmark is trace evidence.
How are hinge lifters useful?
Not fot fingermarks!
Cosmetics, drugs of abuse, grease, pollen, glass, and paint fragments all can be found in finger marks.
