The moral ambiguity of virtually every character in “Secret in Their Eyes” is something star Julia Roberts felt gives the film more realism.

“It widens the palette for people to go back and forth on,” Roberts said at the film’s premiere Wednesday at the Hammer Museum in Westwood. “It makes them think, ‘No, I wouldn’t do that. Wait, no, I would do that.’ You never have a person where you think, ‘Oh, I’m with them.’ Everyone’s performance is so compelling that you really do shift your allegiance the whole movie.”

“Secret in Their Eyes,” based on the 2009 Oscar-winning Argentinian film directed by Juan Jose Campanella, begins with the murder of the daughter of Julia Roberts’ character Jess, an FBI investigator. The film alternates between flashes of Jess’ partner Ray, played by Chiwetel Ejiofor, searching for the killer immediately following the murder and 13 years after the fact.

Writer-director Billy Ray said a movie with morally gray perspectives leads to more compelling viewing for the audience.

“I just think it’s more interesting,” Ray said. “It has this great moral ambiguity, it gives way to great moral clarity and you’ve got to figure out what to do with it.”

Roberts said she could not bring her character home as a parent when playing the grief-stricken Jess.

“I had to surgically separate the two things,” she said. “There was no other way to get in that place and stay in that place if I made it have anything to do with the miracle of my family life.”

“Secret in Their Eyes” is STX Entertainment’s second major release after August’s sleeper hit “The Gift.” Also in attendance at the premiere and after-party at the Hammer Museum were pic’s Dean Norris and Zoe Graham; STX’s Robert Simonds, Sophie Watts, Adam Fogelson, Cathy Schulman and Oren Aviv; and IM Global’s Stuart Ford. The movie also stars Nicole Kidman, Michael Kelly and Joe Cole and opens Nov. 20.