DNA Evidence week 9 IFS

DNA Evidence week 9 IFS

1. Police personal sent to scene.

   • Report back to Senior Investigating Officer (SIO)
   • Police interview complaint to gather intelligence and investigative informaiton

2. Evidence samples to collect in Burglary case.

   • Tool Marks. (Entry)
   • Fingerprints.
   • Footwear marks
   • Glass
   • Hair and Fibres
   • Possibly blood. Blood pattern analysis.

3. forensic Evidence.

   • Biological.
     • Blood.
     • Salvia
     • Touch DNA.
     • problems with biological evidence.
       • Contamination from other areas or owner
       • Range of evidence types which may not be limited to your level of expertise
       • Price
   • Trace.
     • Hairs.
     • Fibres.
     • Glass
     • Paint.
   • Marks and impressions.
     • Tool
     • Finger.
     • Footwear.
   • Accelerants and explosives
   • Digital.
     • CCTV
     • Mobile Phones
     • Growing as an evidence type
   • Others
     • Firearms
     • Weapons
     • Drugs
     • Poisons
     • Documents
     • Can have chemical depending on scene

4. Evidence types in order of success rate.

   • Semen (90% dna success rate)
     • Blood (88%)
       • Chewing gum (86%)
         • Cigarette butts (74%)
           • Fingernail scrapings (mixed dna profile, 69%)
             • Comb/razor (53%)
               • Hair with root (50%)
                 • Saliva (42%)
                   • Hair without visible root (20%)
                     • Watch strap (8%)
                       • Cigarette lighter (7%)

5. Evidential DNA recovery techniques.

   • Directional searching
   • Swab
     • Wet, dry, single, double
       • Wet swab being used first, dry swab the excess liquid.
     • Swab material
     • Only recover DNA evidence
   • Tape lifting
     • Mini-tapes has an adhesive which doesn't interfer with the DNA
     • Joint evidence recovery, alongside DNA could pick up hairs fibres.
   • Direct Sampling
     • Buccal swab example
   • Methodically search the crime scene

6. Control DNA Recovery technique.

   • Complaint- Elimination sample
   • Suspect- PACE sample
   • Buccal scrape
     • Omni swab
     • FTA Card
   • Plucked hairs
   • Blood samples
   • Anti-mortem samples
     • Toothbrush
     • Razor
     • Hairbrush
     • Relatives DNA samples

7. UK

   • NDNAD
     • Established in 1996
     • Home office is Custodian of the NDNAD
     • DNA profiles from over 6 million individuals
     • Crime Scene samples and PACE samples
   • PED
     • All police personnel
     • SOCO'S are incorporated into the database to be eliminated

8. DNA profiling

   • Sample Colleciton
     • DNA Extraction
       • PCR Amplification
         • Capillary Electrophoresis
           • Electropherogram Analysis
       • DNA Quantificaiton

9. DNA Intelligence

   • DNA recovered from crime scene
   • entered into National DNA Database
   • No match found

10. Familial DNA searching

    • DNA Inhertiance
      • Inherited from parents
      • Relatives more likely to have similar characteristics in DNA
    • Two possibilities:
      • Sibling of offender
      • Parent or child of offender

11. Other interpretational challenges

    • Mixed profiles
      • Contamination
    • Partial profiles
      • Degraded DNA
      • Low template DNA
        • Hugely degraded can use low copy DNA but that comes with alot of errors which is not ideal
    • Related Suspects
      • Identical twins
    • DNA Persistence
      • Legitimate access
    • Secondary transfer of body fluids
    • Mutations- if DNA suddenly chnages

12. 60%- 70% Of crime scenes have DNA

    • Used to identify individuals
    • Exclude individuals
    • Prove family links
    • Present at every crime scene in many different forms
    • Multiple uses: food fraud, security, conservation
      • Immigration cases
    • DNA databases
    • Statistics available- court reporting
    • Technology constantly advancing
      • SNPs
      • mtDNA
      • Y Chromosome
      • RNA
      • RapidHIT (IntegenX)
      • Eurofins 'twin test'
      • Huge area to be developed