When Aaron W. Foster and Barbara (Bobbi) Winn climbed into the back seat of Bill Finney's car on a December night in 1980, they were drunk and literally fighting mad.

"She pushed him; he pushed her and, eventually, he slapped her," Finney, the former St. Paul police chief, told jurors Thursday.

Five months later, in the early morning hours of May 8, 1981, Winn was dead from a single gunshot to the chest in the Maplewood townhome she shared with her three children -- and sometimes with Foster.

More than 27 years later, Foster is on trial for third-degree murder in Winn's death.

Prosecutor Deidre Aanstad and defense attorney Earl Gray both said in opening statements that Foster and Winn had argued at the Tipsy Tiger bar the night she died and that she'd told him to move out.

"How did Barbara Winn die?" Aanstad asked. "Was it murder? Was it suicide? That question can only be answered one way. Barbara Winn was murdered May 8, 1981."

Gray countered that the medical examiner never ruled whether Winn's death was an accident, a murder or a suicide. The manner of death was -- and still is -- undetermined, Gray said.

Foster told Winn's sons and officers then that she had shot herself.

Winn's children told jurors what they heard and saw that night.

Tyrone Winn, then 12, testified that he was awakened by loud voices and what "sounded like a scuffle."

He cracked open the door of the bedroom he shared with his brother, Randy, listened and then heard a loud pop.

"I heard her say, 'Oh Bubbie, that hurt,'" Tyrone, now 39, testified. He and Randy, then 15, ran into their mother's room and encountered Foster.

"Look out, she shot herself," Foster told the boys before running downstairs.

The boys and their sister, Tammi, then 13, found their mother slumped over from the waist.

The gun lay on the floor near her left foot.

Randy picked it up, intending to go after Foster and shoot him, but his brother and sister talked him out of it, Randy Winn, now 43, testified.

Foster came back upstairs and he and Randy laid Winn on the floor. Then Foster took the gun, which Randy had tossed onto the bed and left the house.

Maplewood police officer Steve Heinz testified that he was one of the first two officers to arrive, at 12:23 a.m. May 8.

He said Foster led them to the master bedroom, where Winn's body lay face down, with her shirt pulled up near her shoulder blades.

A bullet protruded from her back, just below the skin, Heinz said. He and another officer rolled Winn onto her back and saw the bullet hole in her chest.

Finney, a sergeant at the time, has been a friend of Foster's since the 1970s. He said he "was very disturbed" when he learned of Winn's death.

He went to her autopsy on May 8 to tell Maplewood investigators about the December incident.

"I wanted them to have enough background for their investigation," he said.

Finney said he was off duty when he picked up the couple at a bowling alley in St. Paul's Midway Shopping Center.

He said he heard, rather than saw, the loud, open-handed slap. "She went into submissive mode," Finney said. "I went into aggressive mode. I pulled to the curb and told them 'Knock it off. Don't make me be a police officer tonight.' I wasn't too happy with either one of them."

Pat Pheifer • 651-298-1551