Fibre Recovery Flashcards
Fibre recovery process
- Process is carried out by ERU- a specialised evidence recovery unit.
- Recover all materials from DNA and body fluids drugs to physical and trace
- This approach is effective ensuring all evidence is handled appropriately and holistically
- Individual experts or reporting officers may supervise to ensure intellectual continuity and suggest alternative methods of recovery
- Once collected evidence is then sent on to the relevant experts for full analysis
7 fundamental principles
- Avoidance of contamination
- Items from different scenes are stored and examined separately
- Item integrity is ascertained prior to examination
- All equipment is laboratory specific and is for the most part disposable
- Work area and equipment is cleaned prior to use
- All equipment is logged and is often bench specific
- All garment worn must be non-shedding
- Case notes will be accurately recorded and include the location and times of any examination work
pre examination checks
- Once examiner is satisfied info is correct the item may be removed from the evidence bag
- The item is then checked again
- It is then placed on a protected and cleaned bench
- The examiner will begin their case notes and produce an annotated sketch of the item and take photos
- The items then divided into examination zones and each is examined by eye and with stereo microscope
- Directional light is best provided using fibre optic units
fibre retrieval- garments
picking taping shaking scraping vacuuming combing
picking
individual fibres, tufts and clumps are picked of using forceps
- Preferred method when tufts or clumps are easily visible and allows exact location to be recorded
- Method of choice for shoes, weapons and other complex shapes and also for pockets when other methods may be difficult
- Often used in conjunction with stereomicroscope especially with items with complex morphology
taping
Adhesive tape is applied to the item
- Most efficient
- Recovers significant loose fibres on the item which might otherwise require significant examiner time to pick individually
Common methods
• Rollering – J-Lar tape is reverse wound around a
roller
• Sheet Support – Tape is reverse stuck onto acetate
• Press and rub – Fairly self-explanatory
• Non-Standard – Various method in use including
specialised tape and wrapping methods
shaking
The item is shaken over clean paper coated bench (often using a huge funnel) any lose fibres are collected. Distribution information is lost.
vacuuming
A specialist vacuum is applied to the item and individual fibres are retrieved from a filter area
scraping
A scraping device is passed over the item in an attempt to knock fibres from the item. Distribution information is lost.
combing
A comb to which a thin layer of clean material is fitted
control tapes
- When working with fabric items it is good practice to prepare a shedding tape and a reference tape
- The former is used to show how easily the fabric sheds and the latter as a reference guide to the nature of the base fabric fibres
sheddability
- A short piece of tape is firmly applied to the item and is stuck to the examination form. The sheddability is the assessed, poor fair or good.
references constituent fibre control
- One or more tapes is prepared as above and this is mounted on an acetate sheet and labelled as a reference sample – The sample should be representative of all fibres within the item
presentation of fibres
Once recovered fibres must be appropriately stored until further information requires complete analysis and comparison as necessary and dependent upon case circumstances
most fibre samples are taped and before exhaustion, the tape is stuck to an acetate sheet and the edges are sealed with further clean tape to avoid contamination
The acetates can be stored for decades in this state or can be assessed immediately
not every fibre present is of significance and this method of presentation allows rapid triage
