I wish I’d had a 10 percent better understanding and insight into the case when I started the movie.

I say that because this has been the most complicated and difficult film I’ve ever made. The story was legally complex and took place 30 years ago. I am not a lawyer. Although my father was a politician and a judge, I do not know the inner workings of the DA’s office or how lawyers and judges behave or bargain with one another.

What’s more, there were only a limited number of people I could talk to. These people were not used to being interviewed and some of them were very careful about what they said. I never pre-interview — I find it takes the spontaneity out of the actual interview. I need to be surprised when I am talking to someone. (The only person I did pre-interview ended up disappointing me with his interview because I had heard him tell his stories once already!)

If I had a 10 percent better understanding of the story at the outset, then perhaps my questions would have been more precise. By the time I’d finished the film, I had a lot clearer picture of what had happened and wished I could go back to my first interviewees with all the new information I’d uncovered.

Looking back, I can see now that the Polanski case brought out a cryptic, haiku quality in everyone. It’s such a delicate case — on so many levels — that people are reluctant to talk about it directly.

Knowing that, I wish I had been brasher and ballsier. But then I might never have got the access that I did. My mother always says, “Why does it take so long? Aren’t you finished yet?!” But to me, documentary filmmaking is a gigantic, three-dimensional puzzle with pieces concealed within cities and people and buried away in articles and court documents. It’s a brilliant adventure.

And then, of course, there’s everything that takes place behind closed doors — the meetings for which there is no written record. Nobody tells you how to go about finding that! But you work it out somehow.

My advice for other people starting out on such a quest? Learn as much as you can — and then dive in.

[PREMIERE SCREENING: Friday, Jan. 18, 6:15 pm — Holiday Village Cinema III, Park City]