Introduction Evidence is the key to solving a crime. Collecting evidence is important because any questions that people cannot answer can be answered scientifically. Crime scene investigators can be trusted as expert witnesses because of their field experience and knowledge of the evidence. There are two main types of evidence that can be used in court: direct and circumstantial. Direct Evidence Direct evidence is evidence that can be collected at the crime scene by investigators, such as: video, audio, DNA, fingerprints, weapons and even the bodies of victims. When collecting evidence, the scene must be kept clear and free from contamination by other people. Investigators can take several hours to collect evidence and understand the crime scene. Direct evidence is based on facts. "An eyewitness to an event is direct evidence, but eyewitnesses are often unreliable... People may lie or not see things as clearly as they believe, especially if an event occurs quickly or at a time of high stress" (V circumstantial...