Briefly explain what is meant by the concept contamination of evidence and provide a
practical example from you working experience or any report in the media.
Explanation and reasons for contamination
When there is a transfer of any material to the original physical evidence.
Contamination is when there is transfer of any other material to the original physical
evidence. Contamination can also happen between two or more items of physical
evidence. Contamination can occur from the time it is found or seized until the actual
analysis or presentation of the physical evidence in court. The collection of any
physical evidence by hand, without protection.
Comments
• Please reference practical examples in your answers. It may well contribute to
additional points. It also indicates that you comprehend the question and will be
able to apply the theory in practice.
• Apply your knowledge when answering the questions.
• Please do not copy directly from the book, use your own words. Always attempt to
be comprehensive when answering questions.
• Read pages 10, 20, 22, 29, 37-38, 42, 44, 72, 85, 113, 134-135 and 140 of your
prescribed book for additional information. This is recommended for examination
purposes.
Question 2
In any investigation the chain of custody is of paramount importance.
• Explain what is meant by the chain of custody
• What should you do to prevent evidence on a fire scene of being contaminated
Answer
Evidence that are ceased or identified at a scene:
• Are recovered
• Stored
• Packaged
,• Analysed
• Transported
• Presented in court
• Without alterations
It is the chronological history of the evidence. If changes are made to the evidence it
should be disclosed. If the integrity of evidence has been maintained physical evidence
will therefore be authenticated. It will prove who had contact with evidence, under what
time and what circumstances; there is no room for negligence and careless handling,
preservation, packaging and transporting.
The investigator on a fire scene should ensure that the chain of custody is maintained,
and to prevent evidence contamination, he or she should:
Establish and maintain strict control of access to the scene. Note that power tools and
equipment using fuel present potential contamination and if they are used, the
investigator should document their use. Wear clean protective outer garments. Use
clean and disposable tools for collecting items of evidence. Place the evidence in a
clean, unused container which should be sealed immediately. Package liquid samples
separately from other evidence.
Comments
• Reference practical examples in your answers. It may well contribute to additional
points. It also indicates that you comprehend the question and will be able to apply
the theory in practice.
• Apply your knowledge when answering the questions.
• Always attempt to be comprehensive when answering questions.
• Read pages 14 and 134 to 135 of your prescribed book for additional information.
Question 3
List the primary objectives and additional objectives of scene investigation.
Answer
Primary objectives
• The objective of a scene investigation is to identify,
, • recover,
• document physical evidence and
• the systematic and careful collection of facts, clues and physical evidence.
Additional objectives of scene investigation can therefore be seen as:
(any six of the seven objectives)
• reconstructing the scene
• ascertaining the sequence of events
• determining the mode of operation of the perpetrator
• uncovering a motive
• discovering what property was stolen, if any
• collecting physical evidence
• determine the actions of the perpetrator
Comments
• Please apply your knowledge when answering the questions.
• Do not copy directly from the book, use your own words.
• Always attempt to be comprehensive when answering questions.
• Read pages 33 to 34 of your prescribed book for additional information.
Question 4
Investigators must always act in an ethical manner. Name six unethical conducts that
investigating officers must withhold them from doing. From the lecturer’s experience
this is extremely important and this questions will be repeated in the examination.
Answer
• Withhold from altering evidence at the scene.
• Placing evidence at the scene.
• Collecting evidence without a warrant.
• Falsifying laboratory examinations.
• Ignoring evidence at a scene.
• Failing to report a colleague, superior or subordinate who engages in any of the
listed activities above.
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