2026 Criminology Unit 3 Notes: Latest with
Summary
WJEC Criminology Unit 3 (2026): Complete Crime Scene to
Courtroom Notes – Personnel, Techniques, Evidence,
Rights, CPS, Trials, Laypeople, Validity, Conclusions,
plus 180 Exam Q&As with Detailed Rationales
.1 – Effectiveness of Personnel (Questions
1–15)
Q1. Name the legal Act that gives police
officers their main powers to stop, search,
and arrest.
A1. Police and Criminal Evidence Act 1984
(PACE).
Rationale: PACE sets out police powers and
safeguards. It is the cornerstone of lawful
investigation in England and Wales.
Q2. What is the main role of a Crime Scene
Investigator (CSI)?
A2. To identify, preserve, collect, and
,package physical evidence from a crime
scene without contamination.
Rationale: CSIs are not detectives; they
focus on forensic recovery. Their actions
determine admissibility of evidence.
Q3. Give one strength of using a forensic
scientist in an investigation.
A3. They provide objective, scientific
analysis (e.g., DNA profiling) that can link a
suspect to a scene with high probability.
Rationale: Objectivity reduces bias
compared to eyewitness testimony. The
Colin Pitchfork case proves this strength.
Q4. Give one weakness of the Crown
Prosecution Service (CPS).
A4. The CPS relies entirely on evidence
gathered by police; if police investigation is
flawed, CPS may still authorise a weak
,charge.
Rationale: The CPS does not gather its own
evidence – a limitation highlighted in cases
like R v. Kilbride.
Q5. Which case demonstrated that police
tunnel vision can lead to a miscarriage of
justice?
A5. The case of Colin Stagg (1993) – police
fixated on him for the murder of Rachel
Nickell.
Rationale: Tunnel vision ignored other
suspects; an undercover operation ("honey
trap") was later condemned by the court.
Q6. What is meant by "contamination" of a
crime scene?
A6. The introduction of foreign material
(e.g., DNA, fibres) or removal of original
evidence by unauthorised people or poor
, technique.
Rationale: Contamination can lead to
wrongful convictions (Barry George case) or
acquittals.
Q7. Name the test the CPS applies before
charging a suspect.
A7. The Full Code Test – includes the
evidential stage (realistic prospect of
conviction) and the public interest stage.
Rationale: This filters weak cases and
ensures efficient use of court time.
Q8. Give one way police detectives can be
effective in a major investigation.
A8. They can coordinate multiple teams
(forensics, witness interviews, intelligence)
and apply for warrants.
Rationale: Leadership and legal powers
Summary
WJEC Criminology Unit 3 (2026): Complete Crime Scene to
Courtroom Notes – Personnel, Techniques, Evidence,
Rights, CPS, Trials, Laypeople, Validity, Conclusions,
plus 180 Exam Q&As with Detailed Rationales
.1 – Effectiveness of Personnel (Questions
1–15)
Q1. Name the legal Act that gives police
officers their main powers to stop, search,
and arrest.
A1. Police and Criminal Evidence Act 1984
(PACE).
Rationale: PACE sets out police powers and
safeguards. It is the cornerstone of lawful
investigation in England and Wales.
Q2. What is the main role of a Crime Scene
Investigator (CSI)?
A2. To identify, preserve, collect, and
,package physical evidence from a crime
scene without contamination.
Rationale: CSIs are not detectives; they
focus on forensic recovery. Their actions
determine admissibility of evidence.
Q3. Give one strength of using a forensic
scientist in an investigation.
A3. They provide objective, scientific
analysis (e.g., DNA profiling) that can link a
suspect to a scene with high probability.
Rationale: Objectivity reduces bias
compared to eyewitness testimony. The
Colin Pitchfork case proves this strength.
Q4. Give one weakness of the Crown
Prosecution Service (CPS).
A4. The CPS relies entirely on evidence
gathered by police; if police investigation is
flawed, CPS may still authorise a weak
,charge.
Rationale: The CPS does not gather its own
evidence – a limitation highlighted in cases
like R v. Kilbride.
Q5. Which case demonstrated that police
tunnel vision can lead to a miscarriage of
justice?
A5. The case of Colin Stagg (1993) – police
fixated on him for the murder of Rachel
Nickell.
Rationale: Tunnel vision ignored other
suspects; an undercover operation ("honey
trap") was later condemned by the court.
Q6. What is meant by "contamination" of a
crime scene?
A6. The introduction of foreign material
(e.g., DNA, fibres) or removal of original
evidence by unauthorised people or poor
, technique.
Rationale: Contamination can lead to
wrongful convictions (Barry George case) or
acquittals.
Q7. Name the test the CPS applies before
charging a suspect.
A7. The Full Code Test – includes the
evidential stage (realistic prospect of
conviction) and the public interest stage.
Rationale: This filters weak cases and
ensures efficient use of court time.
Q8. Give one way police detectives can be
effective in a major investigation.
A8. They can coordinate multiple teams
(forensics, witness interviews, intelligence)
and apply for warrants.
Rationale: Leadership and legal powers
