IMO, if they have someone in custody for a valid reason, that is probable cause. But that is my opinion.
How about Driving Under the Influence? Can I pull all your phone records, credit records, medical records to see who you have called, done business with and what drugs you are taking? Can I then go to the 2nd, 3rd and 4th tier or do I need to find a judge who would say, "what's the probable cause"> just because dirboy sounds dirty or looks dirty or has pals outside the country? It gets complicated quickly.