Depends on where you are with her. If you haven't started her story, I think you first find out about the police by talking to your father (it was a very long time ago, so I could easily be wrong), you can go to the police and ask to speak with the detectives, sometimes they will talk to you, other times not, I don't know if it random, or if they will see you at specific times or days. By general conversation with topics they are interested in, you can raise your reputation with both of them. While exploring the motel, you will get beaten up by some thugs, if you go to the cops (and if your reputation is high enough) they will patrol the roads, the first time will fail and you will lose some rep, so you have to build it back up, the second time it should succeed (this should also open up the motel manager story). After that (if I recall correctly) you have to make progress with your father's lawyer, which can be done initially by meeting with her in her office (ask your dad if you don't know where it is), after a few meetings, you will be able to have lunch with the Lawyer. I don't remember what triggers it, but eventually you find out that the Lawyer and detective York are seeing one another at parties at the Lawyers flat (in the residential zone) on Wednesdays and Saturdays, if you bring booze, you can get invited in which should develop your rep with both. Next you need to raise your rep with Ren (the Lawyers Secretary) and discover that she is a secret graffiti artist by night, you will be given an option on your phone to search for her nightly activities, if you get involved, sometimes the cops will discover you, and you can take the heat for it, if you don't phone your mom, Detective York may give you a lift home, which can turn into sexy times with her (if you have progressed far enough with the Lawyer), in the new update, you have the option to propose Naughtiness with her when meeting with her at the police station, which leads to the file room scene.
This is far from a complete walk through, because I am doing most of it from memory and much of it was many, many updates ago, so I could easily be forgetting steps, but it should at least give you some pointers.
