I was wondering of how this law works for a court scenario I thought up, to see if it would work this way. Let's say a witness, witness A, is going to testify in a criminal case, but another witness in the case, witness B, is going to testify against the defendant, and his testimony, although against the defendant, will incriminate witness A. Can witness A take the fifth, and get immunity from being charged with a crime, if another witness is going to incriminate her in the process of his testimony against the defendant? Let's say this is true and she can get immunity for this. Witness B testifies and incriminates her, but she has immunity from being charged. After the case is over, will the police be able to investigate her for the crime, if the method of discovering her crime, was through the testimony if a witness she was given immunity from? Immunity means you cannot be charged with the crime if the crime is discovered through the testimony of the witness you are immune from? But are the police allowed to use the information in the testimony to investigate her after? Because if immunity means you cannot be charged, does it mean that an investigation can also not legally come out if it? Does immunity from prosecution also legally equate to immunity from investigation, if the only way the police know about the crime, is through the witness, that the person was legally immune from? And perhaps taking the fifth is the wrong term since the fifth is a right for a person to not incriminate yourself. When a witness says she will only testify in case, if she gets immunity from another witness, that law is probably called something else, right? Does anyone know? I cannot find a law that is this specific of a scenario and how it would legally go down.