i crimina investigation
Police O cers
- The first on the crime scene and they have a vital role
- They need to safeguard the public and attend to anyone seriously injured
at the scene (call an ambulance)
- They may need to arrest suspects
- Key job is to secure the crime scene in order to conserve the evidence to
prevent contamination
Key definitions:
The Golden Hour - the name given to the period immediately after a crime is
discovered, when o cers must act quickly to preserve the crime scene. Initial
statements from witnesses and victims are taken.
Police Detectives - they manage a range of criminal investigations (typically
serious or complex crimes). They have specialist departments:
- CID (criminal investigations department)
- Fraud
- Drugs and firearms squad
- Child protection department
Other specialist units include:
- Tra c and mounted police
- Air support and underwater search teams
- Dog handler units
Limitations:
- Criticised for sometimes failing to secure the crime scene and preserve
evidence and failure to investigate crimes
- Such as domestic abuse or hate crimes
- Failures can be due to incompetence in handling evidence or
discriminatory attitudes of individual o cers
- Failures may be due to system-level failures, such as institutional racism
- This was identified in the metropolitan police in the Macpherson
report in the investigation of Stephen Lawrence
- Failure to give stephen first aid at the scene
Crime Scene Investigators:
- Crime scene investigators or CSIs are also known in some police forces as
crime scenes of crime o cers (SOCOs)
- They are usually civilians rather than police o cers. CSIs undergo
specialist training and many have a science degree
- The largest forces employ dozens of CSIs, who provide a 24/7 on-call
, service.
● The CSIs role is to collect and process evidence from crime scenes, as well
as from post mortems and accidents.
- A key responsibility is to preserve evidence in an uncontaminated
condition, since contamination means that it will be inadmissible in
court.
- Crime scene investigators or CSIs are also known in some police
forces as crime scenes of crime o cers (SOCOs).
- The CSIs role is to collect and process evidence from crime scenes,
as well as from post mortems and accidents.
Their main activities include the following:
• Taking charge of the crime scenes, liaising with people to find out what
evidence is required from the scene and deciding how best to obtain it.
• Photographing crime scenes, items and people, such as tyre marks, shoe
prints, weapons, injuries, victims and suspects.
• Recovering physical or biological evidence from crime scenes, including
fingerprints, gunshot and explosive residue, clothing fibres, hairs, bodily
fluids and DNA.
• Packaging, storing and documenting the material recovered from crime
scenes.
• Attending post mortem examinations of suspicious deaths.
• Advising police investigators on the physical evidence, photography and
samples for laboratory analysis.
• Giving evidence in court.
Strengths:
- CSIs may gather evidence that conclusively links suspects to crime scenes
and victims
- The evidence may also prove conclusively that a suspect is in fact innocent,
e.g. when their fingerprints do not match those found by the CSI at the
crime scene
Limitations:
- The work requires specialist skills (such as forensic photography)
as well as patience, meticulous care and attention to detail.
- Failure to collect and record evidence correctly, or allowing it to
become contaminated, can lead to a guilty person going free or an
innocent person being convicted.
- The forensic samples that CSIs handle may put their health or safety at risk
- These include blood and other body fluids, hazardous chemicals,
explosives and incendiary devices, firearms, and ammunition, knives
and hypodermic syringes
- The work may be stressful and emotionally demanding – for example,
having to attend gruesome crime scenes or post mortems
Forensic Scientists and specialists:
Forensic science involves applying scientific knowledge to crime and the legal
system: