Doesn’t he need to be accused of a crime to be prosecuted with probable cause respective to the accusation?
He doesn't need to be accused, just suspected.
Said another way, you are correct, but the phrasing of your question was technically incorrect. Authorities can't go on fishing expeditions. They need to have an articulable suspicion.
On paper we are not a police state. That said, we are in fact a police state, just all the authorities deny it, and claim we are not, etc. The government does not practice any of the restraint it or the law claims.