Actress Jessica Chastain struggled to deal with the media attention following reports her biological father had died earlier this year (13), because she never knew the man.

Michael Monasterio passed away in early February (13) as the Zero Dark Thirty star prepared to attend the Oscars, but Chastain refused to comment on the death and did not attend his funeral in Sacramento, California as she had no emotional connection to the 55 year old.

The movie star, who is known for closely guarding the details of her private life, has now spoken out about the loss in a new interview with Vogue magazine, admitting the added press scrutiny was "very difficult" for her to cope with.

Chastain reveals Monasterio was not even named on her birth certificate, so she had "no proof of anything" about who her dad really was.

Instead, the Oscar nominee insists her stepfather, firefighter Michael Hastey, was the man who helped to raise her, and she credits him as "one of the greatest people" in her life, adding that she felt secure for the first time in her life when he wed her mother, Jerri, during her childhood.

Chastain has never publicly acknowledged Monasterio, who is said to have fathered both the actress and her younger sister, Juliet, in the late 1970s.