If the alleged mastermind of Washington's largest heroin-smuggling ring goes on trial later this year, his defense will be provided by a gut-level courtroom fighter, an openly on-the-make lawyer who was a prosecutor before he took up legal defense work.

Kenneth Michael Robinson, 35-year-old attorney-at-law, relishes the upcoming battle in a case that has a chilling footnote: according to government sources, Robinson's client was allegedly involved in an attempt to assassinate an assistant U.S. attorney, a job Robinson once had.And during almost four years in that job, Robinson earned a reputation as a flamboyant prosecutor who was roughest on drug and murder suspects. He handled -- among other things -- 20 murder cases, bringing home guilty verdicts in all but one.

But a clue to his courtroom personality rests on another statistic: four of his victories were eventually overruled because -- said the appeals court -- Robinson's summary arguments were so filled with rhetoric and emotionalism that juries were unduly influenced.

"I go in swinging with both hands," says Robinson, who shares, along with trial lawyers such as F. Lee Bailey and Melvin Belli, a love for newspaper ink that reflects his theatrical courtoom manner. One writer attributed to him a "swashbuckling rage," Robinson notes with obvious delight. "I like that. I'm sort of a fat Errol Flynn."

Today Robinson is defending the kind of people he once prosecuted. Shortly before he was arrested in late January, Linwood Gray picked Robinson as his attorney after spending several days shopping for lawyers. He liked Robinson, who asked him to take a polygraph exam; Robinson said Gray -- a 34-year-old former mental patient and convicted band robber -- passed the exam when asked whether he was involved in drug smuggling or the shooting of assistant U.S. attorney Barry Leibowitz last December.

Shortly thereafter, Gray was arrested along with nine alleged operatives for running what authorities described as a sophisticated, international ring of smugglers who carried into the U.S. about $30 million worth of heroin over a 2 1/2 year period. Gray denies the charges and also disavows any knowledge of the attempt to kill Leibowitz, who ran the investigation.

"The trial is going to really show who is behind the drug-running ring," vows Robinson, "and it isn't Linwood Gray. We'll also show how the dope was coming into the country and where it was really going, and it wasn't Washington. The trial will show how the people really responsible for the dope were more clever than Linwood Gray and how the Drug Enforcement Administration was duped."

How, one might ask, did Gray know so much about drug traffic if, as he claimed at his arrest, he just worked a $14,000-a-year job running a club on Alabama Avenue SE?

Robinson says Gray was owed a considerable sum of money from a former Washington disc jockey named Bob "Nighthawk" Terry, who helped produce an outdoor concert in 1977. Several months after the concert, Terry disappeared. Some of the receipts from that concert also reportedly disappeared. Neither the money nor Terry have been found.

"We're going to prove that Nighthawk is still alive and well," claims Robinson, who says his client was trying to recover the money owed by Terry. It should be noted that only Gray and Robinson, not prosecutors, say Terry trafficked in drugs.

All this intrigue is a long way from Robinson's South Carolina roots. The son of an in surance salesman, as Robinson puts it, he admits to a rather colorless career as a student. Married his freshman year in college, he was distracted by a full-time job as he pursued a law degree at the University of South Carolina. He often wondered if he shouldn't have followed his original ambition to be a pro baseball player.

After a boring stint at the Interstate Commerce Commission, Robinson learned from a friend how things were done in Washington. He visited his homestate senator, Strom Thurmond, in hopes of making a connection that could land him in the U.S. attorney's office here.

"What's your name?" Robinson recalls Thurmond asking him the moment he entered the senator's office. "Where are you from, what do you want, why do you want it and what's your political party?"

"I'm Ken Robinson, I'm from Greenville, S.C., and I want to be an assistant U.S. attorney in Washington, sir. I'm a Republican and was before it was fashionable. The best trial experience is here, and they're always hiring those Ivy League guys, and I thought it was about time some University of South Carolina boys had a crack at a job here, too."

The Ivy League dig stuck in Thurmond's craw, Robinson remembers; several months later he had his job. One news story describing Robinson's delivery of a closing argument noted that it was presented "with a flair and flashiness rarely see." Later, in private practice, Robinson defended the company of alleged pyramid king Glenn "Dare To Be Great" Turner; Robinson's closing argument brought tears to a juror's eyes and the result was a hung jury. Robinson objected so loudly and often during the other side's final argument that the federal judge had U.S. marshals kick him out of the courthouse.

That kind of behavior earns a lawyer enemies among his colleagues, some of whom accuse Robinson of being a headline grabber who appeals more to a jury's emotion than intelligence. Since he entered private practice with the avowed aim of getting rich and famous, Robinson has won 25 of the 31 cases he's argued before a jury. All but one were criminal cases.

Robinson says he doesn't know if he would have taken the Gray case if the lie detector test had indicated Gray was lying about being involved in the shooting of prosecutor Leibowitz. Though the two don't particularly care for each other, Robinson says after he'd heard Leibowitz was shot, he intended to send him flowers. But Leibowitz was released from the hospital the next day and resumed his handling of the heroin investigation.

"Narcotic cases are the most challenging because you have to take the open anger jurors have -- because everyone hates heroin for obvious reasons -- and displace it," says Robinson, who admits to once going to trial with a man he knew was guilty. "I told my wife after I made my argument that I never felt so hollow, I could barely get the words 'not guilty' out. But he insisted on going to trial, I did the best I could, but he was found guilty."