Jessica Alba’s role in the violent new movie The Killer Inside Me shocked her friends, the actress has said.

“My friends were probably the most taken aback. They were trying to get images out of their head for a while,” the 29-year-old has revealed.

The film, based on Jim Thompson's 1952 novel about a psychotic killer, also stars Casey Affleck and Kate Hudson.

The actress, who gave birth to her daughter Honor Marie Warren in June 2008, has also spoken about how becoming a mother has changed her career choices.

“After I had my daughter, I wanted to concentrate on doing movies with good directors,” Alba reflected in an interview with New York magazine.

“If I’m going to be away from her, it needs to be worth it. I don’t want to be away from her doing some big silly movie where I’m running around in a leotard shooting people for six months. I’m not saying I’ll never do that, but right now, that’s not where my head’s at.”