Have you read the fifth amendment yet?Do you often ask that of the police when they discover crime?
Do you ask the firemen who called them after they put out the fire?
why are you more concerned with why a crime was Investigated than the actual crime?
This is not a fire - that's a clear and present danger to society around it - a situation that clearly exists, or it doesn't.
Now, if there IS no fire, yes, who called the fire (that doesn't exist) in is a valid question.
As we've seen from people getting damaged by police who lie, whether or not there is sufficient justification for a warrant or for an investigation absolutely is a question for the police.
Why I am concerned with why a crime is investigated - especially when the evidence points to no crime - is because I believe in the constitution and a citizen's freedom from harassment from the government.