Can "for" replace "behind"?

1. "For" is okay but I prefer using "behind" in this context. "The reason" and "due to the fact" are used correctly.

2. You don't need a comma after Ruby.

3. Who does "she" refer to? There are two names but only one of them had been a licensed therapist. Ruby might be assumed to be female – if so, the sentence could be written this way:

Franke, 45, said that the reason behind Ruby and Hildebrandt managing to skirt any real punishment was due to the fact that Ruby had been a licensed therapist.

Much clearer.