As the court-martial of Marine Cpl. Lindsey Scott headed toward its conclusion yesterday, a government prosecutor told the all-military jury that Scott raped his neighbor's wife for sex and intended to kill her to keep her from testifying against him.

Scott's defense attorney John F. Leino ridiculed that suggestion in his closing argument, declaring: "Where's the indication that he's a criminal? He's nothing but a good marine. He's nothing but a good person, married and with a baby on the way {at the time of the 1983 attack} . . . . One bright day he decides to kill his neighbor's wife?"

The rape, sodomy, abduction and attempted murder case against Scott goes to the jury at Quantico Marine Corps base today after 16 days of testimony from 36 witnesses -- a trial record that is likely to translate into a transcript of about 2,500 pages. Scott, whose testimony at the original court-martial in 1983 is thought to have damaged his case, did not take the stand in front of the jury this time.

One of the most highly publicized military cases in recent memory, the case of United States v. Scott is fraught with conflicting testimony, witnesses' improved memories and recurring, sometimes subtle suggestions that racism played a role in the investigation and prosecution of Scott, who is black. What's more, there is virtually no physical evidence against Scott; there is no semen, hair, clothing fibers or blood linking him to the victim.

But closing arguments by both Leino and the military prosecutor, Maj. Ron N. McNeil, suggested that the case boils down to one critical question: Who is more credible, the victim who tearfully identified Scott as her attacker or the former Zayre store detective who testified that she saw Scott shopping around 8:15 p.m. on April 20, 1983, the same time the woman says she was abducted?

The former store detective, Cynthia K. Ausby, testified at Scott's first trial in October 1983 that she could not remember the date she saw Scott at Zayre. At that court-martial, Scott was convicted and sentenced to 30 years at hard labor.

Several months later, Ausby said, her memory was jogged by store records she had not reviewed before testifying, and she had become certain of the date she had seen Scott.

Last summer, the nation's highest military court set aside Scott's conviction, and the Marines subsequently ordered a retrial.

Stressing that Ausby did not recall the date she had seen Scott until about 10 months after the fact, prosecutor McNeil yesterday called Ausby's new testimony "incredible" and suggested that she had changed her story to help a civil rights activist named Lori Jackson who, he said, is Ausby's friend. Jackson has worked on Scott's defense since September 1983.

McNeil further cited the testimony of two Northern Virginia police officers and a polygraph examiner who asserted that Ausby is untruthful.

Three other witnesses, including a Prince William County police officer, testified yesterday that they think Ausby is truthful.

Leino hinted that prosecutors had tried to suggest a racial motive for Ausby's testimony by citing her friendship with Jackson, to whom they referred several times as a civil rights activist. Both women are black.

But he backed away from the issue as soon as he raised it, commenting obliquely: "I hope {the prosecutors} don't mean what I think they're trying to imply. Let's just avoid that."

Leino suggested that Ausby had been branded a liar in retribution for her testimony on Scott's behalf, and stressed that Ausby had been adamant about her testimony.

"I don't care if she's Mata Hari, I don't care if she's {former Charles Manson associate Lynette} Squeaky Fromme {who tried to assassinate President Ford}, there are certain things that she knows."

Against Ausby's testimony is that of the wife of a military policeman who worked with Scott and lived in his apartment complex in Prince William County in 1983.

In the current court-martial and the one in 1983, the woman said she was certain that Scott is the man who tricked her into accepting a ride, raped her, cut her throat and left her to die in a remote, wooded area of the Marine base.

Her identification of Scott was less certain on two occasions before the first court-martial. Although she picked Scott out of a group of photographs and a line-up, both times she also selected a second man who was not a suspect in the case.

"In her mind," Leino said, "someone has to pay." Although Scott's attorneys have returned frequently to the theme that Scott was singled out by overzealous law enforcement officers at Quantico, Leino said yesterday that he is "not suggesting there was some conspiracy."

Leino referred to the testimony of an NIS agent who acknowledged that because the woman equivocated in her early attempts to identify her assailant, she had not made a positive identification. "Is that proof beyond a reasonable doubt?" Leino demanded.

However, he referred several times to the fact that the preponderance of government witnesses were law officers, adding that the "victim became a victim twice" -- once by her attacker and once by the prosecutors and investigators whom she trusted to bring the right man to justice. He referred to the Naval Investigative Service, which handled the investigation, as the "Naval Insinuative Service."

Prosecutor McNeil said that unlike Ausby, who identified Scott nearly a year after she said she saw him shopping, the victim identified Scott when her memory was "current" and "fresh." He called the woman "shy, gullible and a perfect victim."

For the first time, McNeil also offered a possible motive for the attack -- an element previously notable by its absence. Although he acknowledged that "we don't know why he did it," McNeil added, "We think the motive was sex . . . and he intended to kill her. Then he was surprised the next day when he found out she was alive."

McNeil also stressed the victim's detailed description of the interior of Scott's car, given to investigators shortly after she was found dazed and bleeding and taken to a hospital. She later picked the car out of a parking lot and identified it as the vehicle in which she was raped and sodomized.

The victim "clearly was with Corporal Scott that night and Cynthia Ausby was not," McNeil said.

Leino hammered at the police agencies involved in the investigation of Scott, accusing them of settling on him prematurely because he was a convenient suspect and they could make a plausible case against him.

He chided them for not having seized all of the clothing Scott had worn the night of the attack; for not taking photographs that supported agents' testimony that the front passenger seat of Scott's car, where the rape is alleged to have occurred, appeared to have been wiped down; and for concluding on the basis of a composite sketch that Leino said resembled a "generic" black man that Scott was a suspect.

"They either didn't go far enough or they didn't want to go far enough or Lindsey Scott is innocent," he said.

Leino emphasized the absence of incriminating evidence, pointing out that the one Negroid hair found on the woman's clothing was not Scott's or his wife's. He added: "How can it be that there's not a drop of blood . . . not a speck" on Scott's clothing. The woman was cut deeply in the neck and a doctor testified that she bled profusely.