What is evidence?
Evidence is defined as "any material that serves as the basis of providing the truth or falsification of a fact in issue."
Each piece of evidence should tend to prove a material fact. When you think about it, every piece of evidence discovered will mean something to the case. Each piece becomes a part to the puzzle (the crime) and has its own little story to tell. Our job is to find the pieces and put them back together so they tell us the true story.
Many divers with a little training and experience become quite good at finding evidence or other artifacts because: (1) they become comfortable in their underwater environment, and (2) they use proper search techniques. But that's where their knowledge and training usually stops. The question comes up "Now what do I do with it?" Well you don't just "grab-and-go" anymore. Those days are gone due to the increased investigative requirements placed on us as Underwater Criminal Investigators by the ever-demanding legal system. Evidence has to be properly handled and preserved in order to be presented as a piece of the puzzle and a fact of the case.
Grab-and-Go Recovery Method
The grab-and-go method is just what it sounds like. Divers searching for something, go to the surface once they find it without any thought or further investigation. Part of the reason for their reaction is the excitement of finding what they were searching for. Actually, when the item is located your job has just begun, not ended. Let's slow down, take our time and bring to our dive site the professionalism it requires. Why? This method guarantees:
Loss of trace evidence
Loss of physical evidence
Loss of documentation and information needed for your crime scene report and crime scene sketch
Loss of professionalism
When looking at all the losses you have, you can't help but see that you lose every time you "grab-and-go" to the surface with a piece of evidence.
So, slow down and do it right. As divers and as true professional Underwater Criminal Investigators, we want to be a part of the investigation team and contributors to the case. Not a liability.
Special Note: Your conditions might dictate that you grab the evidence and go to the surface for safety reasons such as when diving in strong currents, depth, etc. When faced with these conditions, the rule is, "do the best you can and stay safe". However, most of your assignments wont be in such conditions, so do it right.