Television cameras were rolling Nov. 27, 1982, when a crowd of demonstrators, gathered to protest a scheduled march by the Ku Klux Klan in downtown Washington, turned ugly and went on a rampage of destruction and looting.

The cameras captured on film a group of men as they smashed the windows of a U.S. Capitol Police car, turned it over and removed some of its contents. Three weeks later, police arrested a man identified from the film, a 21-year-old unemployed construction worker named James Martin.

Now, almost two years later, Martin is the last of 19 persons to come to trial on charges stemming from the disturbance. Yesterday, Martin was found not guilty.

The complex task of prosecuting numerous defendants, many charged with group break-ins and thefts, and tying them to specific criminal acts has contributed to long delays in Martin's trial in D.C. Superior Court, authorities said.

Martin's attorneys raised a novel defense. They claimed that in an incident later that day police pushed Martin through a storefront window and beat him in front of news cameras, and that police have manufactured the case against Martin because they fear retaliation.

In closing arguments to the jury yesterday, a government prosecutor called the claim that police were improperly motivated a "smokescreen" that is "nothing more than an illusion."

"The police department is not out to get James Martin," said Assistant U.S. Attorney Elizabeth Trosman.

In addition to Martin, 18 persons were arrested and charged with crimes in the incident. Charges against five defendants were dismissed later. Of the remaining defendants, 10 were found guilty and sentenced to probationary terms ranging from six months to three years. Two were convicted and given prison terms ranging from six months to 12 years.

One other defendant, 27-year-old Gordon Tillman of Baltimore, charged with burglarizing a bicycle shop, allegedly failed to appear in court for trial and a bench warrant was issued for his arrest in May, according to court records.

After the disturbances, Martin lay in Howard University Hosptial where he was treated for deep lacerations through some of the muscles in one arm.

A hospital worker summoned police after spotting a police badge in Martin's possession, prosecutors said. Police confiscated the badge, as well as three videotape cassettes stolen from the overturned police car, which had been dispatched to the scene with technicians to make independent films of the disturbances.

After four days in the hospital, Martin was released. Police investigators, meanwhile, sifted through the many pieces of evidence stemming from the disturbance, including the news films and still photographs taken by a bystander.

On Dec. 17, 1982, Martin was arrested at his home and charged with destruction to the police cruiser, for which he could have been sentenced to up to 10 years and fined $5,000 if convicted, as well as with stealing the badge and videotape, an offense that carries a penalty of one year.

Martin also was charged with burglary in the break-in of the bicycle shop, for which he is scheduled to come to trial in March.