The unknown fate of two trained dolphins who were releaased into the open sea is haunting the strange trial of a former research student who is trying to establish in court that animals too, are people.

For the prosecution and presiding Judge Masato Doi, the case of the state of Hawaii vs. Kenneth Le Vasseur is a simple matter of grand theft. Le Vasseur and another former student, Steve Sipman (who is to be tried separately in February), are accused of removing two Atlantic bottlenose dolohins from the University of Hawaii's marine laboratory at Kewalo Basin May 29.

But Le Vasseur want to use the trial to present scientist's observations that dolphins are quick to learn, have a brain-weight-to-body-weight ratio second only to human's, apparently have rudimentary language, seem capable of abstract thoughts and have been known to rescue drowning humans.

The defense would like to argue that these and other traits amount to evidence that dolphins have a level of intelligence that makes it wrong for humans to exploit them for amusement, educational or research purposes.

"We didn't steal them," he said in a newspaper interview two days after their release, "We gave them back."

The two 26-year-old graduate students said at the time that they held "a moral and philosophical commitment to the idea that man had no right to capture or hold in captivity intelligent, feeling beings."

Le Vasseur and Sipman lived at the marine laboratory and were in charge of cleaning the separate tanks which housed the two 8-foot, 300-pound female dolphins, known as Kea and Puka. When their supervisor inspected the tanks on May 29 he found that Kea and Puka had been replaced by two small inflated toy dolphins on which had been inscribed the words, "Slave No More."

Whatever sympathy may have existed for Le Vasseur and Sipman probably has been dissipated in Hawaii by the widely reported assertions of Louis M. Herman, the animal behaviorist who directed the dolphin research program, that Kea and Puka in all likelihood were killed by sharks after their release.

Herman's speculation was based on the fact the the two dolphins were from the Atlantic Ocean and would have had to recognize the calls of Pacific dolphin species with which/they were unfamiliar.

"Dolphins are social hunters, depending on one another for location of schools of fish and cooperating in the catch by surrounding the school so all can feed," Herman wrote in a "requiem" for the two dolphins in The Honolulu Advertiser. "To find other dolphins she (Kea) would have to realize that they were somewhere out there in that vast unknown and search for them."

Puka was never seen after her release, but Kea was spotted swimming offshore the same day, and Herman organized an attempt to recapture her. He testified Wednesday that the dolphin, which years before was injured by sharks in the Gulf of Mexico, had one eye closed and fresh wounds on her flank.

It probably was the success of the dolphin's training that prevented her recapture. According to testimony, Kea swam for hours around Herman and others from the laboratory, nuzzling her former trainers, and accepting food from them.

But she was trained in captivity to back away from a net into a holding area until her tank could be cleaned, and she backed away from the nets that were put out to recapture her in the ocean. Kea finally disappeared on May 30, shortly before a commercial fishing boat with larger nets arrived.

Defense attorney Jack Schwigert, who has won a number of environmental cases here, hopes to introduce scientific testimony which will refute Herman's theory that the dolphins either starved or were killed by sharks.

But Judge Doi, who wants to limit the trial to the grand theft issue, has so far blocked most of the testimony about the dolphins' supposed fate. He has also imposed a gag order on both attorneys to prevent Schweigert from elaborating to the press on his novel defense. He also has denied defense motions aimed at producing records intended to show that the dolphins were mistreated in captivity.

Doi did allow Schweigert to question prospective jurors for a time on their feelings about persons who would release creatures from captivity. But when Schweigert asked for more time in which to establish a defense based on dolphins' having human rights, the judge rejected the request as irrelevant and said that dolphins are not human beings under Hawaii's penal code.

Schweigert also lost a series of other legal maneuvers, one of them an attempt to get the Hawaii Supreme Court to delay the trial. The attorney said he wanted to seek federal relief based on the 13th Amendment to the Constitution, which prohibits involuntary servitude or slavery.

The case has attracted interest from environmentalist groups here, notably Greenpeace, an organization known for its efforts to stop the killing of humpback whales. Ross Thornwood of Greenpeace said today that he hoped the trial would become "a forum for animal rights," and said the two released dolphins "had been kept in solitary confinement for 7 1/2 years."

Herman and his associates at the laboratory have depicted Le Vasseur and Sipman as resentful inadequate students who were retaliating because they had been given 30 days' notice of being fired a day and a half before the release of the dolphins. Herman testified that Le Vasseur had caused a number of other problems at the laboratory, including stranding jeeps below the high water mark and wrecking an inflatable boat.

Even if Le Vasseur is convicted the trial may go a long way in establishing the "humanness" of dolphins. Herman was attempting to teach a language to them at the time of their release.

Though Herman has tried to refer to the dolphins as "the animal Puka" and "the animal kea," most of his testimony has described the dolphins in terms more appropriate for humans than for animals.

Herman seemed particularly forlorn on the witness stand as he described his fondness for Kea and his concern for her safety in the open sea.

Telling how Kea had rubbed against him in the water on May 30, before the unsuccessful attempt to net her, he concluded in a broken-hearted voice: "I never saw Kea again."