A leading figure of the Romanian New Wave, Cătălin Mitulescu has had a heralded career since winning the Palme d’Or for his 2004 short film “Traffic.” His first two features, “The Way I Spent the End of the World” (2006) and “Loverboy” (2011), both premiered in Cannes’ Un Certain Regard sidebar. He also co-produced and co-wrote the 2010 Berlin Silver Bear winner “If I Want to Whistle, I Whistle,” directed by Florin Șerban.

Mitulescu’s fourth feature, “Heidi,” had its world premiere this week at the Sarajevo Film Festival. The film centers on an aging policeman on the verge of retirement tasked with finding two prostitutes who are willing to testify in an organizing crime trial. But finding them proves to be easier than convincing them to take the witness stand. Produced by Mitulescu for Bucharest-based Strada Film, “Heidi” stars veteran actor Gheorghe Visu alongside newcomer Cătălina Mihai.

Mitulescu spoke to Variety in Sarajevo about the psychological power play at the heart of his latest film, the distinct pleasure of shooting on film stock, and the unlikely role that Marilyn Monroe played in the making of “Heidi.”

Where did “Heidi” begin?

I think the starting point was when I was doing the research for “Loverboy.” I was working in a police precinct outside of Bucharest. I was very close with an old policeman who told me some stories about how he found some prostitutes, how he tried to help them. He was very interesting as a character, because I felt that he never told me the complete truth. When I was talking with other colleagues of his, they said he had this mysterious past that was very important. He switched sometimes from [doing] his duty to [having a] personal involvement. It was interesting for me.

What’s interesting, too, is to tell a story in that period—spring, when it’s still muddy, on the outskirts of Bucharest. I really felt connected with this place. I wanted to tell a story about it. It feels like nothing happens, but there are some dark stories there.

Like a Romanian “Fargo.”

Somehow, yeah. It came to me: the atmosphere, and the place, with this old man who has power, but is vulnerable. It was very fast. I wrote it, I found a writer I like very much, Radu Aldulescu. He’s kind of Zola-style: he’s in the mud with all his body and soul. He’s much darker than me.

Early in the film, you lay the groundwork for what could have been a more conventional crime thriller—the hard-boiled detective following clues that lead him to the final showdown with the mob boss. But instead, you decided to play a cat-and-mouse game between Visoiu and his reluctant witness, Heidi. Did you ever consider going in that other direction, and make something like a crime thriller?

From the beginning, I was interested in this psychological relationship, and in [Visoiu] as a character. The film is moving in different directions. I like that path. I don’t know how it is for the audience, and how you get these changes. I really liked it because it’s what I was interested in. Sometimes, you are in a situation, and you feel two completely different things. Like [Visoiu]. He can be like a father—he feels like that [towards Heidi]. But then, because of the situation, because of her, it changes completely. Even in real life, you can’t continue on the good path. Sometimes, you lose control and you go in another direction. Even a good man—maybe in 99% cases he’s good and he’s taking the good way. But maybe in 1%, he’s going in a different direction. It’s about that. If you don’t see him in that 1%, he’s a good person. But he’s hiding [something].

You see that play out in the film. Toward the beginning, Visoiu is very paternal toward Heidi, and he stays that way until the point when their relationship becomes something else entirely. But she’s also very provocative with him, very playful. For a large part of the film, she seems to be the one who has the power, because of her ability to provoke him. But ultimately, she’s a woman trapped by circumstance.

She has to survive in a very tough world. She’s fighting. She’s using all her tools to get what she wants—to get out. She wants to get out, but it’s very hard. You need help to get out, but sometimes, if you get that help, you go deeper. Evil has its own dynamic. When you deal with that, it’s very hard to step on solid ground. When you step, you go deeper.

When I gave the script to [Gheorghe Visu], I told him the story. And he said, “A woman like that, it would kill me. What can I do? I’m helpless.” He was talking from his point of view as an old man who had a life of love, so he was very vulnerable. He said first, without knowing the end of the story, “It would be very dangerous to get involved with a woman like that. She would kill me.”

And then you knew you had your leading man. But this was Cătălina Mihai’s first performance. How did you end up casting her?

I found her. It was interesting, because she was from the outskirts where I shot “Loverboy.” She was 13 or 14 then, and she dreamed about [acting]. When she came to the casting, she was really what I was looking for. She got it very quick.

They had great chemistry on screen. Did they have it in real life?

At the beginning, she was more timid, because Gheorghe is a well-known actor, and she was a student. I wanted her to play hard as a character: to charm him, and to play like she’s in control. We talked about many movies, like “Some Like It Hot.” For her it was an inspiration, Marilyn Monroe. She was playing a prostitute on the outskirts of Bucharest, but that thing was very inspiring for me and for her. I wanted to make her shine more, make her sparkle as a character. She’s very generous. She has this glamour, somehow. I wanted that for the character. She got into that with great pleasure.

“Heidi” was shot by Marius Panduru, one of the most acclaimed DoPs working in Romanian film today, who shot two of your previous features. What did you want this film to look like onscreen, and how did Marius bring that vision to life with his camerawork?

It was very nice to work with him. We started in school [together], and we are so in love with the 35mm film stock. We were all the time trying to find the good solution for each movie. At a certain point [shooting “Heidi”], the film stock disappeared somehow. We thought, “Now we have to adapt, let’s try to use digital.” We started talking like that, how we will do this. And after one week of talking, he came to me and said, “I have the solution. We will shoot it on 16.” [Laughs.] I said, “Okay, that’s the solution.”

You cannot replace film stock. On this movie, it was very important that we shoot it on 16. Yes, you can do the color grading and all that. But if you catch the atmosphere on the film stock—this place outside Bucharest, that mud and that haze. I think it was the best solution. It was like we found each other again after a long separation. We really discovered a language that we could use, and we developed that language.