Study note – Opinion evidence
Expert testimony is also called opinion evidence. In English law, a judge can agree to accept opinion evidence from a professional person whose training and experience supports the claim to be an expert. For the duration of the case concerned, that professional is then called an expert witness. Unlike other types of witness, an expert witness is allowed to express opinions as well as discuss facts. For instance, a medical expert might state in testimony that a murder victim died as the result of loss of blood from a wound which, in their opinion, was inflicted by the forceful use of a knife. A digital forensics expert might state that certain, seemingly incriminating, artefacts found on a computer or mobile phone were created by automatic operating system activity rather than by any user.
Physical evidence (sometimes called real evidence); for example, case-relevant documents or other tangible evidence that can be observed and measured. Usually, physical evidence has to be formally produced by a live witness giving testimony as to how and where the physical object was obtained. In many cases, particularly those involving a forensic inquiry, a record of how the evidence has been looked after between its initial discovery and subsequent analysis is required. This record is called the continuity of evidence or chain of custody (CoC). You will look at record keeping more closely in Section 2.
Physical evidence
Case-relevant documents or other tangible evidence that can be observed and measured. Sometimes also called
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Continuity of evidence
A written record of how evidence has been handled and by whom between its initial discovery and subsequent analysis.
Chain of custody (CoC)
A written record of how evidence has been handled and by whom between its initial discovery and subsequent analysis.
Table 5.1 lists a number of common types of physical evidence samples that may be collected at the scene of an incident.
Biological Blood, body fluids, hair
Latent Fingerprints, footprints
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Trace Fibres, soil, glass fragments
Tool and tool mark Tools, traces left by tool use
Firearm Weapons, firearm discharge residue
Drug Solids (e.g. powder cocaine), paraphernalia (e.g. pipe, syringe)
Accelerants Petrol, turpentine, other flammable solvents
Go to module website Activity 5.6 Types of evidence
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