Eric Vetro tells PEOPLE about working with Jolie for around seven months in preparation for Pablo Larraín's new biopic about opera legend Maria Callas

Netflix film Maria, directed by Pablo Larraín from a Steven Knight screenplay, sees Jolie playing the American-Greek soprano in her final days in Paris, as the diva reckons with her identity and life after a glamorous and tumultuous life in the public eye. In real life, Callas died of a heart attack at her Paris home in 1977 at age 53.

“Maria,” Pablo Larraín’s cinematic portrait of opera legend Maria Callas, arrives as the third of the director’s films centered on iconic women of the 20th century.

Finding the breath of Maria Callas was enough to bring things out of Jolie that she didn’t even know were in her.

Angelina Jolie is currently promoting her new movie, Maria, a biopic of opera singer Maria Callas who died in 1977. In an interview with The Sunday Times, Jolie reflected on the difficult conversations she was able to have with her sons while making the film.