The doctor who performed the autopsy on Dr. Herman Tarnower told the jury in the Jean Harris murder trial here today that his four bullet wounds -- including one in the back -- were not, in his opinion, sustained in a struggle.

Delivering the most damaging medical testimony against Harris so far, Assistant Westchester County Medical Examiner Louis Roh said, "The multiplicity of the wounds the person received -- three gunshot wounds resulting altogether in four wounds -- is not altogether consistent with a gun discharged during a struggle. In addition there is the location of the wounds. If two persons are struggling you expect to see wounds in the front part of the body, the chest or the abdomen -- you also expect to see wounds shot at very close range. In this case, you don't have the wounds to the front part of the body, sustained in a struggle between two persons you have described."

Using a life-sized male dummy, Roh portrayed to the rapt jury how he thought the wounds had been inflicted. The doctor, he believed, had been shot through the hand, into the chest as he raised his hand to protect himself, and later in the back as he either bent forward or lay in bed.

The testimony shocked the courtroom. But before Roh was allowed to leave the stand, defense attorney Joel Aurnou staged his own drama. Under cross examination, and following a reenactment of the shooting by Aurnou and a woman approximately the size of Jean Harris, the medical examiner was forced to concede that at least one bullet might have wounded the doctor in a struggle -- and that that struggle might very well have been a suicide attempt.

Aurnou requested that Harris have the right to portray herself in the courtroom re-enactment, but the judge said no. So he chose as Harris' stand-in the judge's clerk, Thomasina Cook, a petite woman slightly taller than Harris.

Arnou placed Cook directly in front of him, instructed her in a whisper to raise her left hand as if she were holding a gun to her head -- and, as onlookers gasped, used his own right hand to grab the invisible weapon. Then he addressed the medical examiner with a note of triumph in his voice.

"Would it be possible for a woman of 5 feet 4 to place a gun to her head and to have someone 5 feet 10 inches attempt to stop that act and, in an attempt to do so, get shot in the hand?"

The medical examiner had to concede the point.

"In medicine, everything is possible . . . in this case, I would say possible, but not likely," he said.

Former headmistress of the Madeira School in McLean, Va., Harris, 57, has been charged with second degree murder in the shooting death of Tarnower, her long-time lover, in the bedroom of his Harrison, N.Y., home last March. The prosection, noting that Tarnower had been seeing another woman, has maintained that Harris shot her lover "intentionally" in a jealous rage. The defense has insisted that the shooting occurred in a struggle as Harris tried to commit suicide. The death of Tarnower, according to the defense, was "a tragic accident."

Taking the stand for the first time today for the prosecution, Dr. Roh, a calm, scholarly witness who is a veteran of "over 10,000" autopsies, seemed -- at first -- to be making an excellent case for the prosecution. He testified to the presence of four wounds in the doctor's body -- in the hand, arm, chest, and back. He also said he was of the opinion that three of the wounds had been fired at "close range." In the chest wound, the markings seemed to be "consistent with a distant shot." (Wounds at close range would be consistent with the defense position that a struggle had occurred; a long-range, wound, to the chest, would not.Neither would a wound to the back be consistent with a struggle, according to ballistics testimony earlier in the trial.)

Roh theorized that the bullet to the hand -- which resulted in a through-and-through wound -- was the same bullet that had penetrated the chest where the wound, he noted, was only one inch deep.

"If a person holds the hand up, this will line up with the wound in the chest," he explained. ". . . The wound in the right arterial chest wall did not penetrate much."

Perhaps some of the doctor's most damaging testimony came in reference to the wound to the back. He said that bullet traveled in a path downward through the back, fracturing three ribs, perforating the lung, and damaging part of the kidney, where it ultimatly stopped. To create that sort of wound, the doctor testified, the gun -- were the victim standing upright -- would have to be placed on top of his shoulder, aiming down.

"The autopsy revealed that the doctor was 5 feet 10," said assistant district attorney George Bolen. "Would these wounds be consistent with wounds the doctor might have sustained while in a seated fashion, bent over at the waist?"

Roh agreed that they could have been.

"If a person is erect, the gun pointing down above the shoulder, if the person is sitting and bending forward, or if the person is lying down in bed and a person holding the gun and stooping over and shooting it . . . that could result in the same kind of wound," Roh said.

But when Aurnou took over -- and began his cross-examination of the witness in tones that caused the prosecutor to object -- the story took a different turn.

After establishing that Tarnower might conceivably have been wounded in the hand as he tried to prevent Harris from shooting herself in the head, Aurnou moved to another point of attack. Attempting to demolish the medical examiner's theory that Tarnower had been shot in the chest at "long distance" range, Aurnou referred to the .32-caliber handgun Jean Harris had been using on the evening Tarnower was shot. According to testimony, that weapon had been loaded with .32-caliber short ammunition -- a size more appropriate for target practice than long distance shooting.

"If you used a weaker ammunition you could get a shorter range -- and a shorter range of powder and smoke?" asked Aurnou, attempting to show that the type of ammunition might misleadingly indicate the distance from which the shot was fired.

The medical examiner agreed.