Basic rules for admissibility of evidence are competence, relevance and materiality. If evidence is shown to be one of those three, then it is admissible.
Evidence should be considered relevant when it contains any trends within reason to either prove or disprove a particular fact more or less probable. Relevant evidence does not specifically require the gatherer of the evidence to undoubtedly prove any particular question in the investigation. Instead, relevant evidence merely needs to hold some piece of pertinent information pertaining to even the smallest aspect of the investigation.
For instance, in the case of a robbery, someone who heard the defendant boasting possible criminal intent would be considered a relevant witness. Again, the plaintiff who in this case would be the employee directly involved at the establishment being robbed, would obtain relevant evidence. Alas, someone involved after the crime, i.e. – a merchant who happened to sell the defendant an item that would normally be out of their grasp of gaining financially, would hold relevant information that would be considered evidence. As you can tell, relevant evidence does not have to come directly from the crime scene itself, nor does it have to be obtained from a specific time period.
Evidence would be considered material when it is offered to either prove or disprove a specific fact that is presented in a case. For example, in a murder case, an eye witness may testify that he saw the defendant’s car drive by the victim’s apartment several times prior to the murder would be material to prove the fact that the defendant was in the area at the time of the murder. However, this may or may not have any value to whether or not the defendant actually did murder the victim. Issues in the case will be decided by pleadings, any formal stipulations or admissions, and applicable law in that area. For example, if the defendant admitted that he was in the area at the time of the murder but had...