The actor who plays CSI's chief crime-scene sleuth has a long history in law enforcement. Sort of. Years before William Petersen became Gil Grissom, he stalked Hannibal Lecter in Manhunter and made his mark in the 1985 action-thriller To Live and Die in L.A. In fact, Petersen still speaks fondly of the latter, which arrives Dec. 2 on DVD. "It's got one of the best car chase scenes ever," he says. "And it shows the seedy side of L.A. It's a perfect '80s movie."

TV Guide Online: You played a federal agent in To Live and Die in L.A. Did that help you snag your CSI role?
Petersen: Not so much. I played a Secret Service agent investigating counterfeiting. That's what the Secret Service does, apart from protecting political figures; it deals with the Treasury.

TVGO: That movie is a modern-day Western. Only with a Wang Chung soundtrack.
Petersen: Right!

TVGO: So could you explain the lyric "Everybody Wang Chung tonight"?
Petersen: Offhand, I would say it has to do with masturbation. It came about at around the same time as Frankie Goes to Hollywood. There seemed to be a year there where every song was about masturbation.

TVGO: So when in doubt, chalk it up to the safest sex?
Petersen: That's right.

TVGO: Grissom is a scientist. When you were in school, how did you do in science?
Petersen: Terrible! I'm not sure I ever passed a science test. I just didn't have any interest in it. I didn't see it applying to my life in any way.

TVGO: Some folks claim CSI has made science cool with kids. Do you agree?
Petersen: I do. I think that for the first time in a long time, people can see the practical application of science. My wife is teaching a high school biology class in Chicago in the public schools, and she'd show them episodes the first year. And I could tell from the response we get from parents and children that it must be cool.

TVGO: Now that you play an überCSI, could you get away with murder if you wanted to?
Petersen: I don't think I could get away with it, but I certainly would know what not to do.

TVGO: One thing I've learned is not to leave semen everywhere. DNA and whatnot.
Petersen: (Laughs) Keep your semen at home. Where it belongs.

TVGO: Will you stick with TV for a while? Or are you itching to do movies?
Petersen: I go where the stories are. I'm not "itching" to do anything.

TVGO: How many times have you seen your name misspelled as Peterson, with an s-o-n?
Petersen: Oh, probably a thousand. See, we're Danish. Anytime you see an "s-e-n," you'll know it's Danish. And when you see an "s-o-n," it's Swedish.

TVGO: I think you're a great Dane.