ABSTRACT
The law defines the type of behaviour and mental states that must be proved if someone is to be found guilty of a criminal offence. It also shapes the process by which investigators go about the task of locating and gathering the evidence needed to do this. The rules of evidence mean that courts can hear any information that is both relevant to the case and admissible in law. The test of relevance and admissibility are sufficiently wide to mean that under the right circumstances almost any type of information can be presented to a court as evidence. As a consequence, the range of information that is of interest to investigators as potential evidence is very wide. Furthermore, the problems of investigation are not limited to evidence-gathering. Information that would fail the test of relevance and admissibility if it was presented to a court as evidence can still be used by the police to make progress in an investigation by increasing their knowledge of an offence or an offender. For example, an anonymous telephone call to the effect that a person has controlled drugs in their home falls well short of the standards that would enable it to be used in evidence against that person. It may, however, lead the police to locate the drugs and charge the person with an offence based on evidence of possession. The anonymous information is therefore of very high value to the investigation even though it is of no evidential value.
