Producer George Stevens, Jr., sat pondering his latest effort. It is the story of a little Southern girl's murder and the conviction and lynching of a Northern Jew.

Why had he been drawn to "The Murder of Mary Phagan"?

"It has to do with my fascination with the outsider," he said, "from my association with my dad in movies like 'Alice Adams,' 'A Place in the Sun' and 'Shane.'"

There are different kinds of outsiders. Sometimes they are like Shane, the reluctant Western hero who rode into the valley one day and saved the homesteaders. The right man at the right place at the right time.

Then there are outsiders like Leo Frank. In 1913 he was in Atlanta running a pencil factory. He was a Yankee in the South. He was Jewish. And he was running a plant that took Southern girls off the land and put them into sweat shops, a symbolic deflowering of Southern maidenhood.

One of the girls was Mary Phagan, age 13. She was killed at the plant after collecting her wages from Frank, $1.20 for 10 hours' work. It was the turn-of-the-century South, and Leo Frank was a Jew from Brooklyn, and the citizens of Atlanta were angry. He was the wrong man in the wrong place at the wrong time.

"It was a long time from conception to realization," said Stevens. "In 1982, {director} Billy Hale and I were talking about things to do and 'Mary Phagan' came up." A change in NBC management circles moved it along, and this week the five-hour miniseries airs in two parts, tonight from 8:30 to 11 and Tuesday from 9 to 11:30 (avoiding the State of the Union address on Monday).

Stevens co-wrote the screenplay with Jeffrey Lane from a story by Larry (Lonesome Dove) McMurtry. He has assembled a wonderful cast, headed by his friend and sometimes golf partner Jack Lemmon.

Lemmon has the role of Georgia Gov. John Slaton. After Frank was convicted and sentenced to be hanged, it fell to Slaton to have the sentence carried out or to modify the sentence.

The second half of the drama is dominated by Lemmon's portrayal of a man who did not seek controversy but who handled it conscientiously when it found him.

Lemmon was effusive in his praise of the cast surrounding him and the overall quality of the film. "There are aspects of this production, if I were sitting as a member of the Academy and this were a feature, I would think of a number of Oscar nominations the film deserves: The set design, wardrobe -- let alone the acting -- were all top drawer." Since it's a TV miniseries, he presumably hopes the Emmy people will pay close attention. The audience too.

"My only worry," said Lemmon, "is that we're so used to looking at TV and not thinking. This show is like a good novel. If you can get through the first 50 pages, you'll love it."

The first half of the story is a knowing and deliberately-paced portrait of Atlanta and the circumstances leading up to Mary Phagan's killing. The film was shot in sections of Richmond that still resemble Atlanta of 75 years ago.

There are fine touches in the first segment. The pencil factory was effectively recreated in an abandoned tobacco plant. And there are scenes that add texture and context, such as the Confederate Memorial Day celebration at which the widow of Stonewall Jackson is introduced and cheered.

Stevens surrounded Lemmon with one of the best ensembles Lemmon said he has ever seen. A number of the faces are fresh, and others are pleasingly familiar.

Leo Frank is played by Peter Gallagher, and Wes Brent, a reporter following the case, is played by Kevin Spacey. Stevens was impressed when he saw them performing with Lemmon in "Long Day's Journey Into Night." Spacey, the current bad guy in the "Wiseguy" series, met Lemmon when he was 15 and still prizes the autographed 8-by-10 glossy taken at the time.

Frank's wife Lucile is played by Rebecca Miller, daughter of playwright Arthur Miller and photographer Inge Morath. Hugh Dorsey, the hyper-ambitious prosecutor, is played by Richard Jordan, who was Michael J. Fox's uncle in "The Secret of My Success."

Robert Prosky plays Tom Watson, the political boss, and Paul Dooley has the role of private investigator Williams Burns.

Sharp-eyed viewers will even catch Virginia Gov. Gerald L. Baliles among a group of delegates from various states who interrupt a dinner party to protest the imminent execution of Frank. Baliles is the fellow from, of course, Virginia.

The period costumes were the responsibility of Judy Moorcroft, who has worked on "A Passage to India" and "The Killing Fields."

Director Hale, whose credits include "Lace" and "Lace II," grew up in Marietta, Ga., about 50 miles from where Frank was lynched in 1915.

Stevens' background in film and television is a rich one, going back to the days when he worked with his director-father on movies including "Shane,", "A Place in the Sun," "Giant," "The Diary of Anne Frank" and "The Greatest Story Ever Told." He paid tribute to his father in a praiseworthy film of his own: "George Stevens: A Filmmaker's Journey." He's been nominated for Emmys 16 times and won three. He took home an Oscar for a film produced under his supervision by the U.S. Information Agency and was founding director of the American Film Institute. He initiated the Kennedy Center Honors and the AFI Life Achievement Award -- Lemmon will be the 1988 recipient.

It all adds up to an engrossing five hours that works at many levels.

"There are no loose ends in the plot," said Lemmon. "Everything ties together. On one level, it's a damn good whodunnit."

If the plot of "The Murder of Mary Phagan" is tidy, the legal case is not. Viewers will be no more certain of Frank's guilt or innocence after five hours of television than historians and others are after 75 years of controversy.

"We're not trying to say he was irrefutably innocent," said Lemmon. "Slaton commuted Frank's sentence to life in prison -- he didn't pardon him. But there was not in his opinion enough to even dream of saying, The man's guilty -- hang him."

Slaton arrived at his decision at great sacrifice. He was an enormously popular governor -- he carried 140 of 143 counties -- and higher office seemed within his reach. Unlike heroes Lemmon has played before, the truth-seekers in "Missing" and "The China Syndrome," Slaton did not take it upon himself to poke into the Frank case. The case came to him in the final days of his term.

"I think Slaton was a moral man, a decent man, suddenly confronted with a set of circumstances," said Lemmon. The handling of the case "threatened what he basically believed in -- the judicial system."

The Frank case is peppered with fascinating footnotes. For instance, the most damaging testimony presented against Frank came from a black man. "A black testifying against a white was a stunning aspect of the case," said Stevens. Some who have studied the case say it was unprecedented in Georgia.

Frank is believed to have been the only Jew lynched in the United States, and the Anti-Defamation League was formed as a result of the case.

Following Frank's lynching, there was a notable exodus of Jews from Atlanta, although his widow continued to reside there.

In the course of the teleplay, two black men appear to be likely fall guys in the case, but it was Frank who was targeted by authorities early on. "The notion at the time," Stevens said, "was that a black wasn't a sufficient bounty for the death of the little girl."

These are heady days for Jack Lemmon. The AFI Live Achievement Award is but weeks away, and he speaks of it as an ultimate honor.

"It's the biggest kick I've ever had," he said, not to play down his two Oscars ("Save the Tiger," "Mister Roberts"). "At this point in my life, I'm dumb enough to think there's a couple of decades left." He hasn't found his next role. "But I've got a lot of nervous energy, and there's only so much golf you can play."

Meantime, he can watch his son, Chris. He's featured weekly in Fox Television's "Duet."

Lemmon said he neither discouraged nor encouraged his son to go into show business. "I made it clear -- if you wait on tables, anything you do, try to be the best you can be. The main thing is to have a passion for what you do.

"I'm lucky. I love acting with all its frustrations. I just prayed he'd be good ... And I think he is. He's a tall, good-looking kid, with lots of personality."

Chris vaguely resembles his father, but it's his acting -- his gestures, expressions and timing -- that bring out the Lemmon heritage.

When his son decided on acting, the senior Lemmon suggested he might want to use his middle name and bill himself Chris Boyd. "He rejected the idea," said Jack Lemmon.

"I think it hindered him in the business to be my son," said Lemmon. "Chris agrees too. There's an onus. It might open a few doors ... but he's got to be better, you know. People will say, Let's see what the star's son can do."

Chris is on television each week, but this is his father's first appearance in more than a decade.

"George is an old pal," said Lemmon. "Three years ago we were playing golf and he asked me to read the story. Then when he had a script he asked me to read that and wanted to know if I'd be interested. We were talking about it as a feature film, but to do it in 2 1/2 hours would castrate the story." A TV miniseries was the answer. "Every now and then I do television for this reason," he said.

For Harvard-educated Lemmon, born in Boston 10 years after Frank was lynched (he'll be 63 next month), preparing to play Slaton was a large part of his limited exposure to the South of Mary Phagan's day.

"I haven't been South much," he said. "I was impressed by the feeling, the division between North and South in 1913, and how much that influenced the feeling against Frank.

"He was dead before he started."