Criminal, in fact most, if not all investigations are comprised of basic elements. Those are as follows, in no particular order.
Who? Who is involved? All persons involved have a story to tell about the event. You need their stories.
What? What happened, what was taken, damaged, said, etc. Pretty big category as you might guess.
When? When did the main event occur? Were there other times leading up to or after the event of note?
Where? Is there more than one location involved?
How? How did the event occur? What are the mechanics, trajectories, etc.
All of the above have to be found out and reported on in a clear, and concise manner. If there is evidence to be collected, it must be properly documented, collected, and if necessary, turned into the proper authorities. Providing you were dumb enough not to call them when you found the stuff!
By following these simple steps, there have been many times in my career where a defendant has been exonerated. There also have been times where the charges were not appropriate for the act. And of course there were times when it was not as bad as the prosecution defined it, it was worse! To know, is the key to be able to defend.