Who hired Ida Sessions and why?
Chinatown is one of my favourite films of all-time and I've seen it quite many times. But there is still something about it's plot that I don't quite understand and that is, who hired Ida Sessions to impersonate Mrs. Mulwray?
I suppose most viewers (myself included) assume it must’ve been Noah Cross and/or his associates in land scheme. But what's his angle there? Why would Cross want to get an investigator involved in this, especially if he already knew that Mulwray had to be killed because he was standing in way of their land scheme? Or did Cross kill him not because of land scheme but because of dispute about Kathrine? But even so, what was he trying to achieve by hiring Gittes through Ida Sessions? Or was it someone else who hired Ida Sessions to impersonate Mrs. Mulwray?
I suppose one could also just say that maybe it's one of those noir mysteries like in Big Sleep where everyone is lost in the complex plot, but given that this is inciting incident of the film and how meticulously constructed Chinatown is, I just feel that there probably is logical answer to this question.