"I came to the show with an open mind," said director David Greene. "I challenged the writer. Jeffrey MacDonald is a likeable man. He's a man who couldn't have done such a thing. But the man who couldn't have done it did."

That's largely the course Greene expects viewers to follow if they tune in "Fatal Vision" (tonight and Monday at 9 on NBC), a miniseries based on the Joe McGinniss best-seller. And be advised that even if, after the two- night, four-hour viewing you decide that MacDonald is guilty, your patronage of the TV movie -- like readership of the book -- will still have helped finance MacDonald's defense.

The subject of McGinniss' and the film-makers' portrait is Dr. Jeffrey MacDonald, a former Green Beret captain convicted of the uncommonly brutal murders of his pregnant wife and two daughters at Fort Bragg, N.C., in 1970.

Newcomer Gary Cole plays MacDonald and Oscar-winners Karl Malden and Eva Marie Saint play his parents-in-law, who first supported his claim of innocence but then led a nine- year drive to bring MacDonald to trial.

MacDonald for a time enjoyed the support of a nation of TV viewers following an appearance on "The Dick Cavett Show." The Army had placed and then dismissed charges against MacDonald, leaving for many the impression that arresting MacDonald was easier for the Army investigators than finding the Manson-like crazies the captain claimed had invaded his home.

"Nine months after the unsurpassingly brutal killings, you see him on TV getting laughs and smiling and lying about a lot of things," recalled Greene, such as the wounds he supposedly suffered at the hands of the family's assailants. "Every time Dick Cavett mentions his family, he bites his lip . . . You see an incredible performance by a man who's lost his family but is enjoying the limelight."

If the unsolved killings were a curiosity for the viewing public, they were an obsession for the victims' family. MacDonald's father-in-law reviewed the transcript of the Army hearing in the case, concluded that MacDonald had killed his daughter and grandchildren and began his nine-year quest.

Greene read the transcripts too. "He was my lead character," Greene said. "I was looking for the human side of him . . . This is a man who managed to escape justice for nine years and then was convicted in six hours (of jury deliberation). The evidence is irrefutable." After the Cavett interview, Greene said, MacDonald emerged as a popular figure, seen as a victim of the Army, which was not enjoying a shiny image during the Vietnam war. And he's used his money to perpetuate the idea of his innocence.

"He's wealthy from the sale of the book," said Greene, referring to an arrangement in which both MacDonald and McGinniss share in the book's profits. "If you were in his position, what would you spend it on? Lawyers to defend yourself . . . He won't stop till he runs out of money."

According to McGinniss, MacDonald has shared about 25 percent of the book's earnings, or $93,000. MacDonald also stands to get 40 percent of the proceeds of the sale of the book to NBC, McGinniss said. NBC paid $130,000 for the rights to the book, according to McGinniss, a transaction that is complicated by a prior contractual claim by Dell publishers. Dell has claimed 75 percent of the TV movie money, leaving McGinniss and MacDonald to split 60- 40 a sum of less than $30,000 after agent's fees.

And there is further complication. MacDonald, unhappy with the way the book turned out, has sued McGinniss and his hard-and soft-back publishers seeking a total of $35 million. Proceeds from the book and TV miniseries help MacDonald assert his innocence as well as hassle the author. McGinniss, meanwhile, has countersued.

"He's frustrated and angry and facing the rest of his life right there" in a federal penitentiary at Bastrop, Texas, said McGinniss. He is serving three consecutive life terms.

A laudable cast and production staff has been assembled to do the MacDonald story. Greene is a four-time Emmy winner for "Roots," "Friendly Fire," "Rich Man, Poor Man" and "The People Next Door." He also did "Rehearsal for Murder" starring Robert Preston a couple of seasons past and "The Defenders" many seasons ago. John Gay ("Run Silent, Run Deep," "Separate Tables," "Sometimes a Great Notion," "Hallelujah Trail," "Soldier Blue") adapted the McGinniss book. In addition to Malden and Saint, Barry Newman and Andy Griffith play key parts.

Cole is another story. "He's never done a film before," said Greene. "He's worked in Chicago theater . . . We all felt the part of Jeff MacDonald required an attractive man -- attractive to women. We wanted a hell of a good actor, a charming man. We auditioned some 20 actors, some more well known." But they lacked a trustworthiness and innocence Greene felt the part required.

Then an NBC casting agent sent over Cole. "It was like Christmas," said Greene. "He started to read, and he was so right. I asked him, 'How long have you been in Hollywood?' He said, 'Since 6 o'clock this morning.'"