So you seem to be claiming that these are distinct legal categories which affect the admissibility of evidence at trial. I don't think this is true; as far as I am aware, prosecutors and police can freely share information collected in different cases as long as that evidence is all disclosed to the defendant prior to trial (and early enough for the defense to prepare or seek a continuance etc.).
For example, it's legal (per the Supreme Court) to take DNA swabs from arrestees without a warrant even if no charges are brought, and all such DNA evidence is by default loaded into a national database known as CODIS. Your DNA data, according to a majority of the Supreme Court can legally be archived, looked at whenever law enforcement wants, shared, and used for other purposes than that which it was originally obtained for.
http://www.hamptoninstitution.org/dnadatabases.html
So again I ask, do you have something to back up your claim about things being different in 'most american states' or were you just saying you didn't think it worked that way?