The use of forensic science in the CJS

Forensic

• From the latin word forensis

• Science is used in connection with the administration of law

  • Criminal law

  • Civil law

• Forensic science has strict guidelines as to who is an expert

Forensic science theory

• Locard’s principle of exchange

  • “Quiscunque tactus vestigia legat“ —
    “When 2 objects come into contact, each will leave a trace of itself upon the other”

    “Every contact leaves traces“

Roles in forensic science

• Police

• Forensic labs

• Research

• Other

Crime scene investigators

• Photography / Sketches

• Physical evidence

• Chemical evidence

• Biological evidence

• Fingerprint knowledge

• Legal knowledge

• Criminological knowledge

Types of crime

• Volume crimes

  • Generally property related

  • Burglary

  • Vehicles

  • Criminal damage

  • Not cordon used

  • Only masks and gloves worn

• Serious/major crimes

  • People related

  • GBH

  • Rape

  • Murder

  • Cordons are used

  • Full PPE (white suits etc) used

From crime scene to court

• Location of exhibit and recovery from scene

• Forward to appropriate lab for experiments

• Analysis of exhibit and interpretation of results

• Results reported to police

• Results presented in court

Who requests forensic expertise

• Prosecution

  • Police

  • CPS

• Defence

  • Solicitor

  • Barrister

• Court

  • Judge

  • Magistrates

  • Coroner

Forensic science duty

• Duty is to the court not the customer

• When in the witness box tell the truth, the whole truth and nothing but the truth

• Science provides evidence to help the court make decisions — opinions always based on fact, supported by research

Rating evidential value

• DNA: Biological, High

• Urine/faeces: Biological, medium

• Tox (Blood, hair, urine): Chemical, medium

• Fire/explosives: Chemical, low

• Footwear/tyre/tool: Physical Medium

• Fingerprints: Physical, high

• Hair: Physical, low