The discovery of a physics professor's corpse in an office at one of California's booming suburban universities has unleashed a bewildering tale of Vietnamese espionage, embezzlement and suggestions of odd life styles, all expected to confront a jury in a murder trial set to begin Monday.

The victim, Edward Lee Cooperman, has, in the months since his death, been portrayed by friends and enemies as a key player in a struggle to maintain contacts between the United States and Vietnam. For seven years, from his office on the campus of the California State University at Fullerton, he allegedly made at least a dozen trips to Vietnam and funneled thousands of dollars in aid to its communist government.

His accused murderer, Minh Van Lam, 21, has become a symbol of the tragic fallout from America's last war.

Lam immigrated to the United States with his family five years ago, enrolled at Cal State Fullerton and, according to his attorney, became Cooperman's protege. The professor is said to have bought the student a motorcycle, given him money and encouraged his studies.

Just how such a relationship might have lead to the shooting of Cooperman with a .25-cal. pistol one Saturday morning last October perplexes many associated with the case, and has led to a number of exotic theories.

Preparing for the beginning of trial in Orange County Superior Court, Deputy District Attorney Mel Jensen has said little about what might have motivated Cooperman's accused killer.

Instead, Jensen has focused on changes in the suspect's story. Lam first reported Cooperman's death to police at least three hours after the murder, and said he had left the professor alive around noon and returned to find him dead. Later, after asking officers if the murderer could be identified from an analysis of the bullet, Lam told police he shot Cooperman accidentally during a self-defense game that the professor encouraged.

In the last weeks of his life, friends said, Cooperman, 48, became obsessed with the possibility that he might be assassinated by right-wing Vietnamese displeased by his dealings with that country's communist government. He had formed the U.S. Committee for Scientific Cooperation with Vietnam in 1977, and shipped computers, soil-testing equipment and medical gear to Hanoi.

When contacts in the Federal Bureau of Investigation suggested he might be in danger because of these activities, friends said, Cooperman mounted lights around his driveway, cut back shrubbery, closed his drapes at dusk, and began keeping an irregular schedule. He bought several weapons and took up National Rifle Association target practice, they said.

Some friends suggest that a rightist group, perhaps with help from an Asian gang, killed him despite his precautions. One county jail inmate has told investigators that Lam confessed to carrying out the orders of a Vietnamese gangster, but his story has been questioned.

Alan May, Lam's attorney, has studied Cooperman's life style for clues to support his client's innocence. May has noted the black leather jackets Cooperman gave to young Asian friends such as Lam. Cooperman's desk contained tags for the pistol that killed him, and for a .38-cal. revolver, as well as some homosexual-oriented magazines and pictures of young men in black leather jackets.

In papers filed with the court, May has suggested that Cooperman may have staged an elaborate suicide, not only because of unbearable pressure from his right-wing critics, but also from his communist friends.

"The Vietnamese government became skeptical of him because he had not delivered all he should and had seriously dipped into the funds for himself and his friends rather than use them for Hanoi's benefit," May argued.

According to this theory, Cooperman coaxed Lam into helping him practice disarming a potential assassin, then intentionally caused the gun to go off in hopes of becoming a martyr to his political causes. This theory suggests that Lam never realized that the seeming accident actually was a suicide.

To Frank Wilkinson, who worked closely with Cooperman in the U.S.-Vietnam Friendship Association, this theory is "just absurd."

But May remains firm in his theory of a young defendant misused by a mentor sunk deeply in paranoia. "He would end the dilemma as a martyr of the left rather than be exposed," May concluded of Cooperman. "The defendant became his instrument of escape."