What is the law when during a traffic stop for non use of a turn signal turns into a criminal case after the fact no body has warrants.

If the officer had reasonable suspicion to believe illegal activity (ie smell of marijuana) can detain for investigation.  However, the stop can't last any longer than a normal traffic stop.   So depending on why the officer felt there was reasonable suspicion and how long it took to get the dog there and do it sweep it may or may not have been proper.