Any issue in a criminal case can be proven in two different ways, that is by presenting direct evidence or by circumstantial evidence. Direct evidence directly proves that fact without requiring the jury to draw inference from the facts or other evidence.
The circumstantial evidence on the other hand tends to prove the issue by relevant fact or series of facts from which the jury can infer the existence of the fact in issue. This was discussed in the cases of Shepherd v R (1990) 170 CLR 573. See also Doney v R (1990) 171 CLR 207; Festa v R (2001) 208 CLR 593; Myers v DPP  AC 1001; R v Spina  VSCA 319).
Many criminal cases do not have eyewitnesses who can directly prove the facts of the case or who can tell the accused in the crime charged. Most of the time, the prosecution relies on circumstantial evidence to prove their case. In such cases, the jury will be directed to draw inferences regarding the guilt of the accused.
When the prosecution relies on the circumstantial evidence to prove his case, the judge on the other will have to direct the jury that the only inference they can do is about the guilt of the accused, nothing else and that they must be satisfied of the facts upon which they based their inferences beyond reasonable doubt. Whenever the jury finds any reasonable explanation for this series of circumstances considered as circumstantial evidence, they have to declare the accused as not guilty.
Disclaimer : This article is just a summary of the subject matter being discussed and should not be regarded as a comprehensive legal advice for you to defend yourself alone. If you are charged with criminal offences, it is recommended that you seek legal assistance from criminal lawyers.