Evidence plays a vital role in proving or disproving the facts of a case. There are different types of evidence, the most common being witness testimonies. Apart from testimonial evidence, physical evidence and documentary evidence are also highly valued. Different types of evidence can be broadly categorized as direct and circumstantial evidence. Evidence that proves the case directly is direct evidence. If an eyewitness testifies that he saw the accused killing the victim using a sharp knife, such a testimony amounts to direct evidence. If a witness testifies that he heard the victim yelling for help, and saw the accused running out of the victim's house, with a blood-laden knife, the testimony amounts to circumstantial evidence. While the first testimony is a 'direct proof' of the fact that the accused has committed the murder, the second testimony 'suggests' that the accused has committed the murder. In the latter case, the testimony has to be linked to the facts of the case through reasoning. So, hearing the victim's screams and seeing a person running out of the crime scene with the murder weapon suggests the fact that the latter has committed the murder, though the witness has not seen the suspect committing the crime. It can be said that circumstantial evidence is that evidence which proves the surrounding circumstances, from which the main fact can be inferred through reasoning. Otherwise known as indirect evidence, it comprises certain facts, from which the fact to be proved can be inferred. This type of evidence is defined as follows: "Information and testimony presented by a party in a civil or criminal action that permit conclusions that indirectly establish the existence or nonexistence of a fact or event that the party seeks to prove." It is used in both civil and criminal cases. Circumstantial evidence can be of different types. The main ones include human behavior, forensic evidence, etc. Human Behavior: The circumstantial evidence example cited above shows the behavior of the accused after committing the murder. In some cases, witnesses may testify that they found the accused near the crime scene at the time of the murder, or the accused was behaving strangely or suspiciously before and after the murder. The behavior of the accused towards the victim may also amount to circumstantial evidence. For example, a husband who is accused of murdering his wife was cruel towards the latter, way before the murder; or a person accused of rape, used to stalk the victim for a long time. It may happen that certain suspects get highly nervous when being questioned about the crime. If an otherwise poor person is found splurging money after a robbery has happened in the neighborhood, it amounts to circumstantial evidence. Forensic Evidence: Forensic evidence amounts to circumstantial evidence, as it needs to be corroborated with witness testimony. Such evidence includes fingerprints, and biological evidence like blood, semen, hair, skin, and nail; weapons, tire marks, foot marks, etc. Other types of physical evidence, like photographs, video recordings, etc., are also considered circumstantial evidence. A suspect can be held guilty solely on the basis of direct evidence, or on the basis of direct evidence combined with circumstantial evidence. A combination of different pieces of strong circumstantial evidence is also enough to influence a verdict. However, weighing its importance is the responsibility of the jury or the judge. While some pieces of circumstantial evidence are very strong, some are too weak. Usually, verdicts are not made solely on the basis of a single, but weak circumstantial evidence. The degree of probability plays a major role in rating the innocence or guilt of the accused. Degree of Probability: The type and nature of circumstantial evidence may vary from one case to another. So, each and every piece of evidence cannot be considered equally important. For example, a witness testifies that he saw the suspect near the crime scene, immediately prior to the commission of the crime. In another case, a witness testifies that he saw the suspect standing near the victim's body with a blood-laden knife. In both cases, the testimonies do not prove that the suspects are the killers, as the witnesses have not seen the suspects killing the victims. However, from their descriptions, it can be inferred that the suspects are the killers. If you compare both testimonies, the probability of the suspect's guilt is very high in the second case, as compared to the first one. In the first case, the suspect could have been an innocent person who happened to be near the crime scene. In the second case, the suspect could have been an innocent person, who found the victim dying, and removed the knife from the latter's wound. If you compare both examples, the probability of the suspect being innocent is very low in the second case. If that probability is corroborated with equally important circumstantial evidence, it is enough to establish his guilt. But, the suspect in the first example may not be convicted if there is no other evidence to corroborate the testimony. In short, strong circumstantial evidence is enough to hold a person guilty or liable. In fact, it is much stronger than direct evidence (like eyewitness testimony) in some cases. It may happen that the eyewitness is not genuine. But, if properly corroborated with other evidence and facts, it can be more reliable, so as to form the basis of the verdict. Even this type of evidence needs authenticating witnesses. Credibility of the testifying witness can be a problem in case of circumstantial evidence too.