Where can I find the "legal" and "professional ethics" in which a state investigator for the State of Iowa is bound by. Surly they don't have total ammunity to any of their actions.

Specifically:

1. If one was arrested 4 times, can that investigator prior to a trial, share that information (details and names) of the alleged accused with anyone on the street?

2. I was arrested for dependent adult abuse in Jan. 2009, for alleged abuse which happened in early 2006. The dependent adult during an interview (sound mind and body) stated he was not abused in any manner. How can I be arrested without having an interview? I was not even notified by the state that I was under any investigation til my arrest 3 years later. What rights do I have?