The woman who lived with accused murderer Bernard C. Welch testified yesterday for the prosecution that her common-law husband was not at home the night government prosecutors allege that Welch fatally shot Washington physician Milchael Halberstam.

Linda Susan Hamilton told a packed D.C. Superior Court that when she awoke on the morning of Dec. 6, the man she knew as "Norman Heiman" and the couple's silver Mercedes were gone.

The emotional testimony by Hamilton, who had been granted limited immunity by the U.S. Attorney's office in exchange for her cooperation in the case, served to tie together day-long testimony by government witnesses linking Welch to the scene of the Halberstam shooting. The noted cardiologist and author was slain last Dec. 5 outside his Northwest Washington home after he walked into his house and surprised a burglar.

For nearly eight hours, a parade of government witnesses -- including several of Halberstam's neighbors -- told the jury that they had heard and seen unusual things on the night Halberstam was shot: gunshots, tires screeching, thudding sounds, and finally, the dark figure of a man running by a bedroom window. There also was testimony from the man who found Welch lying behind a large garden planter and called police, who came and arrested Welch.

It was also a day in which part of Welch's possible defense was hinted. Defense attorney Sol Z. Rosen told reporters that he will prove Welch was in Northern Virginia until late afternoon that day and not casing Halberstam's neighborhood, as the government contends. Halberstam was shot at 8:30 p.m.

"It's strictly a circumstantial evidence case," Rosen said, "All they're proving is there's a lot of junk in this case, and that they found a body."

But it was Hamilton's 20 minutes of testimony against the father of her three infant children that was the most dramatic.

A slightly plump woman with strawberry blond hair, Hamilton has always claimed she knew nothing of Welch's alleged criminal activities, and never knew he called himself "Bernard C. Welch." She could testify against him because she never married Welch and Virginia law does not recognize common-law marriages, according to prosecutors.

She said that police contacted her on Dec. 6, the morning after the Halberstam shooting, and asked her to come to D.C. General Hospital.

"The detective took me into one of the wards and brought me over to a bed," Hamilton said in response to a question posed by prosecutor Jay B. Stephens.

"Did you see a person there?" Stephens asked.

Welch, who has pleaded not guilty to murder, burglary and gun charges in the case, watched passively as Hamilton replied in the affirmative.

"Did you recognize the person?"

"Yes," the 32-year-old woman replied.

"Was that the person that you'd been living with?"

"Yes."

"By what name do you know that person?"

"Norm Heiman."

Stephens told Hamilton to look around the courtroom. "Can you identify the person?" he asked.

Hamilton sighed. In a faint voice, she looked to where Welch was sitting by his attorney, Sol Z. Rosen. "He's over next to Mr. Rosen," she said.

Two of Halberstam's neighbors testified they heard gunshots on the night of the shooting and one of them said she looked outside her window and witnessed a dark figure running with his fists clenched and wearing a down-filled parka.

A third neighbor, Joanne Schlegel, who lives at 5006 Dana Pl. NW, near where the dying doctor slammed his car into a man he said was his assailant, testified that she, too, heard gunshots and later saw a screeching car's headlights shine into her yard.

One of her friends, Jack R. Mulford II, said he later walked outside and "heard moaning noises.

"I made out the form of a body," Mulford testified. "I stood there petrified . . . then ran inside and called police."

Shortly thereafter, according to police testimony, the incapacitated Welch was found lying behind a large garden planter. Police said he was wearing a down-filled parka.