Biel reveals she had to turn to the Psycho star's grandson for information as she prepared to play Miles in the biopic.
The actress says, "Vera Miles wasn't interested... Vera is alive and did not want to speak to me because she doesn't have a public life and is not interested in a public life.
"I don't think that was an insult to me but her grandson was available and so I picked his brain for hours. He's married and was very nice and (a) very respectful guy, and he was very unsure about me at first. He is very protecting of his grandmother, but he was the best historian on her career and who she was at the time of Psycho.
"Her life is exactly what she wanted. I feel it's very challenging to have a private life. It's been very hard for me to have any sort of privacy in life. I get that it's a balance you have to try and create but it's very hard."