When A Tough Cookie Crumbles

(CBS)  On "CSI: Crime Scene Investigation," Marg Helgenberger plays the hard-boiled, cynical and quite single Catherine Willows, a savvy crime scene investigator who doesn't miss a trick — or a clue.

But in her new film, "Mr. Brooks," Helgenberger plays against Catherine's type: she's a devoted, loving wife who cannot — or will not — see that her husband has a secret second life as a serial killer.

"I think that somewhere she does know that he's got a dark side, but she chooses just not to go there because I just don't believe that she was completely oblivious. But never for a moment believing he was a cold-blooded murderer," Helgenberger told Early Show co-anchor Hannah Storm.

Helgenberger compared the character, played in the movie by Kevin Costner, to the BTK killer, the Wichita, Kansas, man who confessed to 10 grisly murders. During the day, the man, Dennis Rader, held a job with his local government, worked on his church council and led a Boy Scout troop.

"You can't use logic with those kind of minds because they're beyond logic," said Helgenberger. "Obviously, they're beyond the realm of anyone's imagination because it's so disturbing and dark."

Helgenberger said she enjoyed working with Costner, calling it "one of the best experiences I've had working opposite an actor. He was incredibly interested in what I had to say, inclusive of my thoughts and ideas about the film and the story."

Costner, she said, "has got a great boyish charm that was highly appealing. And you know, we have to play this loving couple — and we had a lot of fun."

To see Helgenberger's complete interview and see an clip from "Mr. Brooks," view the video to the right.