The prosecution and defense today wound up two tense days of closing arguments in the trial of alleged Marine turncoat Pfc. Robert Garwood, and the case will go to a five-man jury of Marine officers Wednesday morning.

"A finding of 'not guilty' would not make Bobby Garwood a hero," said John Lowe, the tall, silver-haired defense attorney from Charlottesville, Va., who lowered his voice to contrast Garwood's homecoming after 14 years in Vietnam to that of the American hostages in Iran. "He'd still be a sick man. There'd be no tickertape parade for Bobby Garwood . . . no medals from the president . . . no vindication.

"A 'not guilty' verdict would simply give him a toehold in the face of the cliff he will have to climb in search of some measure of mental health and humanity."

Garwood, 34, the only Vietnam-era prisoner of war to stand trial on charges of collaboration with the enemy while in a prison camp, sat stonefaced in his crisp green dress uniform -- decorated with Good Conduct and Vietnam service medals -- as Maj. Werner Helmer scoffed at defense claims that Garwood was driven insane by Viet Cong torture.

"If he was suffering from all these [mental illnesses] and suicide attempts, that man today would be a raving lunatic," barked Helmer. "He knew what he was doing" when he crossed over to the enemy, deserting his fellow American POWs who were dying "in the muck and the mud and the mire" of a jungle prison camp.

In addition to the collaboration charges, Garwood is accused of striking another American POW. Three other charges against him, including desertion, were ordered dropped for lack of evidence last week by Col. R. E. Switzer, the military judge.

In what has become one of the longest and most complex trials in military history, nine former POWs from Vietnam have faced Garwood from the witness box and recounted how he not only shared a "hootch" (a dwelling) with camp guards but also wore the enemy uniform, carried an AK47 and enjoyed the relative luxuries of a Soviet-made wristwatch, a radio and better food.

They also told how Garwood interrogated them, translating their English into Vietnamese. They said he squatted on his haunches and exhibited other mannerisms of the enemy. The other POWs came to know Garwood as a "white Vietnamese," said one witness.

The defense didn't dispute the testimony. In fact, Lowe argued that all Garwood's actions were compatible with the findings of the four expert psychiatrists. "He was not sick enough to die, but he was not well enough to avoid this identification with the enemy," Lowe said.

Government psychiatrists who examined Garwood disagreed, saying that while he suffered some mental disorders in Vietnam, they were between 50 and 85 percent certain he was able to appreciate the criminality of his actions. But Lowe, who had asked them to quantify their certitude, harped on their average of 77 percent.

"That's one chance in four" that Garwood was not able to appreciate the consequences of his action, he said. "Would you get on a plane without hesitation if there was one chance in four the engine would fall off? Or jump out of a plane if there was one chance in four the rigger said the parachute might not open?" Seveal of the usually stern-faced Marine jurors grinned.

It has come down to a battle of the experts. "This is really a one-issue case: mental capacity," said Lowe.

Garwood returned to the United States in 1979 after slipping a note to a Finnish economist in a Hanoi bar. He was a 19-year-old jeep driver just three weeks shy of rotating home when he was captured on a beach outside Da Nang in 1975. Wounded in a gun battle with VC, he was locked in a cage, starved, tortured, humiliated, urinated upon and thrown in a bed of leeches. Twice he tried to escape, twice he was recaptured and tortured again. Finally, he snapped, the defense has argued.

Garwood told all that to the psychiatrists and his lawyers -- he never took the stand himself. His attorneys feared he would unravel emotionally on the stand, said Lowe.

Defense experts have testified that Garwood remains suicidal and still suffers from a mental disorder sparked by an emotionally impoverished childhood in Indiana and made worse by torture in Vietnam.

You might ask, 'Was he credible when he told the psychiatrists [about Vietnam]?'" said Lowe. "They said he was credible," even if some of the details of his captivity are contradictory.

"If what he told them was candid from his perspective, that's a complete defense . . . it means that when he was in Vietnam, he didn't know what he was doing on a conscious level.

"If you'd asked why he was carrying a rifle for the enemy, he'd have said, 'I'm not carrying it,' but if you'd said 'What about that rifle over your shoulder?' he'd have rationalized it."

Helmer, who used a blackboard as a prop to scrawl, "Insanity Defense," sneered that it was "just the old brainwashing theory brought up to date." Then he scribbled over his words with chalk, and snapped, "We are not dealing here with insanity, but with a smoke screen, and defense witnesses have provided the smoke."

The insanity defense, Helmer said, is "the only game in town and he is going to take it." He addressed the jury like a Marine drill instructor, raising and lowering his voice. "Don't let the experts take away your common sense. This term 'insanity' can be nitpicked to death."

His expert government witnesses had been outclassed by defense experts, but Helmer described them as honest and sincere through possibly confused over some questions. He conceded that Garwood may have some form of mental illness, but dismissed it by saying, "No doubt the accused is suffering from depression of the worst kind, But any criminal defendant is going to be under pressure." He said all Garwood cared about in the jungle was his own survival.

Then came Lowe's turn.

"Please remember," he pleaded. "We don't have to prove he is mentally ill beyond a reasonable doubt, but we did it."

He reminded the jury that it was up to the prosecution to prove Garwood mentally able to appreciate his criminal conduct.

Otherwise, "you have to find Bobby Garwood not guilty. That's the law, whether you have personal feelings or not."