MARRIED TO THE MOB - SORT OF : LEARNING (THE HARD WAY) WHETHER IT'S SMART TO GET INVOLVED WITH WISEGUYS.

Byline: Amy Dawes Daily News Film Writer

For six years, he acted every day of his life in a situation where blowing a line might have meant death.

``You only get one take in the Mafia, and that's the first one,'' laughs Joe Pistone, the former FBI agent whose remarkable undercover work in the New York mob inspired the movie ``Donnie Brasco,'' which opens today.

So persuasive was Pistone's charade that some of his closest Mafia pals didn't believe he was an agent until he faced them in court, where his testimony led to more than 100 convictions.

But that doesn't mean that just because he's spent some time on a movie set that he's angling for a career in the spotlight.

``I don't think I could handle it,'' said the soft-spoken New Jersey native. ``I think I'm a natural at undercover work, but I don't think I'm a natural at this celluloid thing.''

His plight as a man with a price on his head (the mob is said to have a longstanding contract out on him for $500,000) would make public life pretty impractical, anyway.

But that doesn't mean Pistone, who wears a disguise for public appearances, was going to let this whole movie thing blow past him without enjoying some of it.

Earlier this week, he attended the movie's premiere in Los Angeles (``It's only gonna happen once, right?'' he explained), though he ducked out before it was over because, he said, ``I didn't want to be around a big crowd.''

And on the Brooklyn set of ``Donnie Brasco,'' Pistone showed up regularly as a technical adviser, even crossing paths with some of the same wiseguys he had fooled during his undercover days who were also there as advisers.

You ask him where he gets the nerve to take a chance like that, and you realize too late that this is like asking Woody Allen how he comes up with a funny line.

``It's the same kind of nerve you got when you're working undercover,'' Pistone says. ``Besides, who's the good guy here?''

In a strange way, that very question is at the heart of ``Donnie Brasco,'' which offers an unusually compassionate portrait of one low-level mobster in particular - Lefty Ruggiero (played by Al Pacino), who ``vouched'' for Pistone as a guy who should be accepted into the mob and became his Mafia partner for four years.

In the movie, it's the growing attachment between Lefty and Donnie Brasco (the name Pistone took undercover) that makes it so hard for Donnie to ``come out'' of the mob, since he knows that as soon as his true identity is revealed, Lefty will pay the ultimate price for trusting him.

The more time Donnie (played by Johnny Depp) spends with Lefty, a loyal Mafia soldier who's past his prime and not destined to rise in the ranks, the more Lefty appears to be a decent guy dealing with a somewhat poignant set of circumstances.

``I think there's something of Arthur Miller's Willy Loman in the Pacino character - he's at the end of his life and he's still dragging around a sample case and realizing that it hasn't been worth it,'' said the movie's director, Mike Newell.

``He is just the low man on the totem pole who takes orders and pulls the trigger, and he's never been allowed any dignity or expression for his heart. And he has a lot of heart.''

``I think it's a tribute to Pacino,'' says Newell, ``that he manages to keep that balance going between whether Lefty is a decent human being or not a decent human being. And I don't think Pacino would have done the role if he had not found something this original in it.''

Still, the movie makes a lot more of the sentimental bond between Donnie and Lefty than does Pistone's book, ``Donnie Brasco: My Undercover Life in the Mafia,'' which recently has been reissued in paperback.

Toward the end of the book, Pistone writes, ``You can't have those personal feelings in this business. I was not there to be buddy-buddy with these guys. I would not allow myself to become that emotionally attached.''

Speaking by phone from New York, where he was helping to promote the movie, Pistone indicated that his actual feelings lie somewhere in the middle.

``I didn't want to see these guys killed. But at a certain point, you know that the errors they committed in introducing me around ... the consequence for them was going to be death.''

``You gotta be cold not to have some type of feeling when you've spent every day for six years with these guys and you know their whole families.''

``But that's where you have to say, `Well, they'd do it to you, too.' ''

Screenwriter Paul Attanasio's absorbing script compresses some of the relationships in the movie. It was actually Sonny Black, the mob captain played by Michael Madsen, with whom Pistone developed a stronger bond than he did with Lefty.

And, unlike in the movie, says director Newell, it was Sonny who ``got whacked'' as a result of his dealings with Donnie.

``The FBI knew that once they revealed Donnie's identity, the Mafia would do the job for them, without them having to go through the complicated business of court cases,'' said Newell.

``And indeed, Sonny was discovered dead in a rubbish bag, with his hands cut off.''

Pistone didn't want to comment on Sonny. He said a contract was put out on Lefty, but that Lefty was incarcerated before it could be carried out. (He since has died of unrelated causes.)

Pistone said he thinks the movie is ``terrific'' and that ``it sticks pretty good to the book.''

``I don't know anybody who could have played me better than Johnny Depp,'' he says. ``And what can you say about Al Pacino? The other actors were outstanding. It was way beyond my expectations.''

That's high praise, considering the movie was directed by Newell, who as an Englishman and the director of comedic and whimsical fare such as ``Four Weddings and a Funeral'' and ``Enchanted April'' hardly seemed a likely candidate to bring off an intimate portrait of life among New York's Mafiosi.

`` `Four Weddings and a Funeral' made $300 million (worldwide) on a budget of under $4 million,'' explains Newell. ``With profit margins like that, any studio in the world is going to give you a shot.''

Newell said he approached the job of researching mob behavior like an anthropologist. ``I put on my baggy British shorts and my backpack, got into a dugout and went up the river called Brooklyn,'' he said. ``And there I found my tribe.''

Newell had arranged a go-between (named Rocco), but he still found that, like Donnie, he had to go through an extended period of scrutiny before he was introduced to any mobsters.

``For weeks and weeks, I sat around with Rocco, going through endless cups of coffee and copies of the New York Daily News, waiting to prove my credentials.''

``And then one day he phoned me up and said, `I'm going to take you to meet some people,' and I was taken to this social club on a corner in Brooklyn, and there they were - dozens of mobsters in this place with a jukebox playing Frank Sinatra and a bar and bets coming in.

``They were generous and welcoming to a fault, and I constantly had to remind myself that they were very bad men as well.''

CAPTION(S):

3 Photos

Photo: (1--Cover--Color) MOB MENTALITY

Former FBI agent Joe Pistone outsmarted the Mafia for six years to stay alive. In fact, he's still at it. Pistone had to wear a disguise to the premiere of `Donnie Brasco,' which stars Johnny Depp and Al Pacino. He tells Daily News film critic Amy Dawes the story of his undercover days.

(2) Donnie Brasco (Johnny Depp, left), with the help of Lefty Ruggiero (Al Pacino), becomes a ``connected guy'' in the Mafia in ``Donnie Brasco.''

(3) `I think there's something of Arthur Miller's Willy Loman in the Pacino character - he's at the end of his life and he's still dragging around a sample case and realizing that it hasn't been worth it.'

Mike Newell

director