We all know that Lizzie Borden took an ax and gave her mother 40 whacks. But do we know what happened next?

“Lizzie Borden Took an Ax” stars Christina Ricci as this deadliest of daughters, and tells the story of her parents’ grisly murder and her subsequent trial in melodramatic fashion.

Borden, who was accused of killing her father and step-mother in 1892, is portrayed as thoroughly guilty by Ricci, who gives her a sociopathic edge via sly looks, such as when her father is found with his face chopped off.

“What I thought was interesting about playing this part,” says Ricci, “was the question of, ‘How does a person behave once they’re accused of this in trying to convince everyone they’re innocent?’ ”

The film comes off as part horror film/part court procedural, as Lizzie tries to convince the police and her sister that she could never have done such a heinous thing — a defense that doesn’t hold up when we see Ricci strip naked to destroy her father’s face.

The lurid scene was not itself based on evidence but, says Ricci, a likely scenario based on the evidence.

“The best people can do is put all the elements together and hypothesize. [Based on the timeline], there was no way she could have gotten rid of her clothes. So one of the theories is that she committed the crimes naked,” Ricci says. “I’m a pragmatist, so I thought it was smart. You can wash blood off your body, but it’s harder to get it out of clothes.”

Borden was acquitted. Her lawyer made the case that she couldn’t possibly have committed such a vicious act because she was a woman.

Executive producer Judith Verno’s belief in Borden’s guilt comes from her review of police and court transcripts, some of which appear verbatim in the film.

“We added a line which is right out of the real transcript: ‘It’s very hard to imagine that if you found your father dead, on the couch, that you would remain in the house.’ To me, the natural instinct would be to leave the house, because the killer’s probably there,” she says. “That she sat down and remained so calm was very telling.”

Whatever is true about this case, for Ricci, playing Borden was a chance to sink her teeth into a disturbed, possibly psychopathic character. Guilty or not, those are often the most fun for actors to play.

“The most interesting people to play are the people who are really troubled, because most people are reactive,” she says. “The most proactive person is gonna be the person with a lot going on in their mind.”