Twelve seasons ago, Detective Andy Sipowicz came on the scene, and, oh, what a charmer he was.

Balding and full-bellied, NYPD's finest was crass, crude and rude. There wasn't much to love, but viewers managed to find it and kept tuning in for more of "NYPD Blue," the ABC drama that's garnered 20 Emmys during a run that ends this season.

Behind Sipowicz's volatile facade is Dennis Franz, 60, no newcomer to the cop beat. Franz had previously teamed up with "NYPD Blue" creator Steven Bochco for another law-enforcement show, "Hill Street Blues," where he played not one but two officers in the precinct. After an unsuccessful spinoff -- "Beverly Hills Buntz" -- and some other missteps, Franz earned a shield with staying power on "Blue."

Franz isn't sure what awaits him once he turns in his badge -- he's thinking more acting, some traveling with wife Joanie and lots of relaxing. "I'm good at doing nothing," he quipped. But he's ready for the show to end, and he's proud of what he called a "phenomenal run."

Like the steamy show, famous for showing bare bottoms and slinging four-letter words, what follows has a parental advisory: Foul language used; reader discretion advised.

You've been through four partners on the show. Who has been your favorite?

You're never gonna get that out of me! But from Sipowicz, well, he had a real fondness for John Kelly, which was David Caruso's character.

Sipowicz is believable in part because of all the little details viewers have become familiar with -- such as wearing short sleeves with ties, or putting cologne in his armpits. What are his quirks that you love?

Well, I like his insistence, how he's thinking he's right about little things. Like, for one example, his pronunciation of the word "prostate." He was certain it was "prostrate." Even when John Irvin tries to correct him, Andy insists he's right. Irvin even leaves a dictionary open to the correct spelling on his desk, and Andy gets upset and still insists it's wrong.

And where do you get inspiration for those quirks?

It began from our writer and creator David Milch. . . . He was my role model for Andy, so on a personal level I got a lot of inspiration from him. I began to realize that he was ridding himself of a lot of demons through Andy Sipowicz. I also looked to Bill Clark, our executive producer, who used to be a police officer. Between the two of them, I came up with a lot of Andy.

Is there one line you remember that really sums up Sipowicz?

Yeah. [Laughs.] "Ipso this, you pissy little bitch." I said that to Sylvia Costas in the pilot episode. We're on the stand and I don't think she's doing a good job getting the info for our case. So afterward we're in the hall, and she says some legal term -- "Res Ipso Loquitor" -- and Andy comes back with [that line].

With actress Charlotte Ross off the show, your personal life with on-screen wife Connie is less visible. Is that disappointing?

It's a big disappointment. It really came as a surprise. . . . We spent so much time getting the audience to accept this oddball relationship. We worked very hard at that, and I think we won a large portion of the audience over.

Where will this season take Sipowicz? Will we see more tragedy for him?

I doubt that very seriously. I think Steven and I and the writers do not want to see Sipowicz go out on the slab. We want to end on an upbeat note for him as far as what's ahead.

How much did your two previous roles on "Hill Street Blues" help you create the mannerisms of Sipowicz?

Not only those two helped, but Andy Sipowicz is cop No. 28 for me. So all 27 in the past have created those layers.

Terry Wrong, who produced "NYPD 24/7," said the officers he interviewed for that documentary [narrated by Franz] all loved Sipowicz. Wrong said several of those officers have met you when visiting Los Angeles. Do you spend a lot of time with actual police officers around the country?

Hardly a week goes by where officers don't come on the set, swapping stories, taking pictures, giving us attaboys. When we film in New York, they're with us 24-7.

How'd you land the role in the Dixie Chicks' "Goodbye Earl" video?

I was backstage [on Rosie O'Donnell's show] when they were coming off. I oohed and aahed at them, and we both said, "Big fans! Big fans!" And . . . they asked if I'd want to do a video. And they said I'd have to be a nasty guy. And I said, "Hey, I've done that before." Six months later, they said I could be one of the cops in the video, and I said, "No, no, no. I want to be Earl."

NYPD Blue

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The Franz File

Born: Oct. 28, 1944, in Maywood, Ill., near Chicago.

"Blues" he's starred in:

"Bay City Blues" (1983), "Hill Street Blues"(1983-1987), "NYPD Blue" (1993-2005).

Number of Emmys won: Four (he's been nominated eight times).

Hobbies: Snow-skiing, golfing.

Married: To Joanie, since 1995. She has two children, Krista and Tricia, from a previous marriage.