The investigator is tasked to systematically identify and bring together those pieces of information - those artifacts - that can still be found after an event and to synthesize from them a provable hypothesis as to cause. He sets out to achieve this goal through determined and systematic collection and examination of information. The evidence he finds will lead to and support (or lead from and disprove) the causal hypothesis' he makes during the process of investigation. Finding information that evidences cause requires the skills to separate important information from unimportant information, the ability to differentiate between what is useful and what is not. Tools and techniques exist which help to extract information from unusual sources and the mastering of a variety of tools and techniques can distinguish one investigator from another.
Merriam Websters defines "Investigate" as "to observe or study by close examination and systematic inquiry" or "to conduct an official inquiry". The investigator must study closely and systematically, in a scientific way, to find what evidence, if any, is available. He must carefully establish his theory of cause from the evidence, so that he will have a logical defense if or when his conclusions are contested.