I didn’t want to hijack the “Do the police ever really use psychics?” thread. However, it made me wondered if police actually used outside sources as “consulatants” in investigations. Are shows such as “Psych” and “Castle” even probable? If so, how much involvement would they have? In a recent episode of “Castle,” one suspect objected to Richard Castle’s presence during the interrogation because he wasn’t a police detective.
Castle isn’t a consultant. He’s an observer (though obviously the cops think his observations are worthwhile). It’s only a slight exaggeration; police from time to time let writers work with them in order to gather material.
True, but in those cases, the writer shuts up and takes notes, he doesn’t call the cops stoopid and tells them how to run their bidness 
Monk is another example.
Would it make a difference that he had been an actual detective before he left the force?
Anyway, it would only make sense that the police use outside consultants during investigations, especially if they were dealing with a case that involved a subculture or subject that they knew little about. The fact that these experts testify at trial suggests that they were often involved in the case as it was developing.
But that doesn’t mean that they’re in the interrogation room or whatever.
Good question, by the way. I’m interested in the answer.