If William Friedkin had his druthers, he'd be producing and directing live television shows. But live TV is virtually extinct.

If he had his second choice, he'd be making television documentaries. But documentaries are on the endangered species list.

So what do you do if you cut your professional teeth on live TV and documentaries and find those two forms pretty much fossilized?

You go back to television anyway, and you bring with you what you've learned in a somewhat more viable medium -- the motion picture. And, of course, you bring with you what you've learned from life itself.

The result is a TV movie called "C.A.T. Squad," an action-suspense film tonight at 9 on NBC dealing with the exploits of a government-sponsored counterattack group. They are called upon to squelch an assassination conspiracy -- by any means necessary -- thus bringing into play one of Friedkin's favorite themes drawn from life and reflected in some of his best work: It's sometimes hard to tell the good guys from the bad.

"If live TV still existed, I probably never would have gone into film," said Friedkin, whose ventures into movies have included "The French Connection" in 1971, which earned him an Oscar, and "The Exorcist" two years later.

Friedkin worked with David Wolper back when Wolper was producing documentaries rather than miniseries and ceremonial extravaganzas. "That's my second love," said Friedkin.

"Basically, all of the ideas I put in movies came out of local television in Chicago in the '50s. I did 2,000 live shows," he added, recalling presentations that ranged from baseball to the Chicago Symphony to a courtroom drama called "They Stand Accused."

But how could a man Friedkin's age -- he'll be 47 next month -- have directed television in the golden '50s? Simple, really: He started early. He was a teen-ager when he began working in the mailroom of station WGN in Chicago. Before he was 17, he was directing live television.

So Friedkin is coming home to television after nearly 20 years in feature films, without fear of being accused of slumming. "There's a stigma attached -- if you do features, you don't do television. But that stigma is artificially created by directors' agents," he said. "Spielberg does TV. Fellini does television in Italy . . . Ingmar Bergman works for TV."

"C.A.T. Squad" was written and co-produced by Gerald Petievich, who collaborated with Friedkin on last year's "To Live and Die in L.A." Petievich, a former member of the Secret Service, is a fellow with many stories to tell. In "C.A.T." he and Friedkin give us a show that might serve as a sequel to "L.A." or a retooling of "Mission Impossible."

The Counter Assault Tactical Squad is assembled to go after conspirators bent on snuffing out anyone associated with the development of a Star Wars-type weapon system. The squad is led by Joseph Cortese as John (Doc) Burkholder, with Steven W. James as undercover specialist Bud Raines, ex-footballer Jack Youngblood as John Sommers, a weapons and explosives man, Patricia Charbonneau as forensics expert Nikki Pappas and Bradley Whitford as the group's newcomer, linguist Leon Trepper. They are the cats in this cat-and-mouse tale. The mouse -- arch rat, really -- is an assassin named Carlos, played by Edwin Velez.

Friedkin is looking at scripts for further episodes in what could be a limited "C.A.T. Squad" series, and the conclusion to tonight's movie, reminiscent of the closing credits in "Young Sherlock Holmes," strongly suggests an encore.

In a departure from films in general and Friedkin films in particular, there are no car chases and no foul language. But in a nondeparture, the film's good guys employ tactics that blur the line between the good guys and the bad. It's made clear at the outset that the squad is to do anything necessary to stop the assassins, and they leave several conventional rules badly bent if not broken.

"It goes to the theme of the thin line between the cop and the criminal," said Friedkin.

Friedkin began his film career by grappling with a moral question. "My first film was 'The People vs. Paul Crump.' It was instrumental in saving a man on death row. Today I have a different view of capital punishment. Today I think anyone who deals drugs -- especially to the young -- there's no alternative to the death penalty," said Friedkin, a divorced father of two sons, ages 3 and 9.

"The Meese commission," Friedkin somewhat reluctantly conceded, "put its finger on something -- all this exposure to violence has benumbed us. I don't let my 3-year-old son watch anything with violence."

Which means it will be a while before he sees much of Dad's work. Friedkin's films have included "The Boys in the Band" and "Cruising" which, added to "L.A.," "The French Connection" and "The Exorcist," round out a body of work that's not for those of tender years.

But the film he'll probably want his son to see as soon as he's old enough to understand it is "Sorcerer." After the success of "The French Connection" and "The Exorcist," Friedkin could make any film he wanted. So he indulged himself with this peculiarly appealing little movie, which lost money but continues to bring more letters to Friedkin than anything else he's done. "Sorcerer" tells the story of four fugitives who find themselves in a far-down-at-the-heel Latin American town, trying to buy their freedom by driving trucks loaded with nitroglycerine over treacherous roads to help put out an oil fire.

"It's the only thing of mine I can still watch and take pleasure in," said Friedkin. Not to trash his other work -- "'Exorcist' is probably the best movie I've made." But "Sorcerer" is more like his child. "It probably came closest to doing what I wanted. God knows it's far from perfect. It's riddled with structural problems.

"Here were four fugitives riding a keg of dynamite -- a metaphor for the world -- they were different characters who had to cooperate to survive."

Survival, the moral questions, the fascination with policemen and their morally murky world -- it's all there in Friedkin's movies, just as it was all there in his life.

Friedkin was born and raised in Chicago. He acknowledges an early penchant for what he calls knee-jerk liberalism, a disposition that has gone at least a bit conservative.

His mother worked as an operating room nurse, and his father held a number of jobs -- "he never made more than $50 a week."

He and his parents lived in one room; when Chicago broiled in the summer, his family and thousands of others slept in a nearby park. "Today, you can't walk safely in that park."

And Friedkin had an uncle. He was more important to Friedkin than anyone else in the family. "I had an uncle, married to my mother's sister, who was a celebrated Chicago cop," he recalled. "His name was Harry Lang. His partner was Harry Miller. They brought in Frank Nitti, the enforcer."

But under Lang's commendations and acclaim lurked a secret: "My uncle was on Nitti's payroll."

When Lang and his partner brought Nitti in, said Friedkin, there were eight bullet holes in his stomach. No weapon was found on or near Nitti.

"My uncle and his partner went through a departmental review and were busted off the force.

"My uncle then became a bodyguard to Chicago Mayor Anton Cermak in the '30s. He was with him when he was assassinated. The assassin was trying to get FDR and got Cermak instead."

This was the uncle who told Friedkin stories of his exploits when Friedkin was a kid, feeding his growing interest in the cop's world.

"I still have my childhood feelings about him," said Friedkin. "He was a fascinating and frightening figure."