'Forensic' is derived from the Latin word forensis meaning 'giving the opportunity for debate'. It has come to mean something which is 'of the law'. By that we mean some activity which has at its core an association with things legal, usually in the form of evidence that can be presented to the court.
Thus, one definition of forensic science is scientific activity that produces evidence for presentation in court. However, it is also the investigation and development of techniques, tests and information-gathering strategies that will help the detectives and those involved in the prosecution. They must put together a case that will 'stand up in court'.
McKenzie, Ian 1996, Criminal investigation, Wayland, London, p. 5.