Debbie Oliver Fennell, whose ex-husband is accused of smothering two of his infant children to collect $190,000 in life insurance, told a Montgomery County Circuit Court yesterday that on the night their 2-month-old daughter died, Garrett Eldred Wilson gave her several pills he said would help her flu.

Oliver said she never questioned her husband about the tablets and slept so soundly that April 1981 night that she didn't even hear paramedics who were summoned to their home early the next morning to resuscitate their daughter, Brandi Jean.

The first witness in what is expected to be a four-week trial of Wilson on a first-degree murder charge in the 1987 death of his 5-month-old son, Fennell was allowed to testify about the death of Brandi Jean six years earlier because of what prosecutors allege were similarities in the deaths of the two children. Both were originally attributed to sudden infant death syndrome. Wilson, 43, faces trial in September in Prince George's County on a first-degree murder charge in Brandi Jean's death.

In his opening statement, Montgomery County State's Attorney Douglas Gansler portrayed Wilson as a philandering father who dominated every aspect of his young first wife's life and ignored his newborn daughter.

Gansler told the jury that on the nights the two children died, Wilson, normally a "distant, estranged" father, rose--for the first time--to feed the children.

Within one month after the birth of each child, Wilson bought a large life insurance policy on the infant: $40,000 on Brandi Jean and $150,000 on Garrett Michael, Gansler said. And in neither case was the mother of the child aware of the policy.

Gansler also said Wilson was the last person to see Brandi Jean and Garrett Michael alive.

Gansler punctuated his opening by demonstrating how he said Brandi Jean was found lying face down in her crib, fists clenched--his own fists in the air--as if she were in a struggle. The baby, Gansler said, was bloodshot red, her forehead white, signs she could no longer breathe.

In his opening statement, Barry Helfand, Wilson's attorney, questioned the validity of autopsy reports in both deaths. After police opened an investigation of Garrett Michael's death in 1993, the state's chief medical examiner changed the cause of death for both children to smothering and ruled that Garrett Michael's manner of death was a homicide and that the manner of death for Brandi Jean was undetermined.

"This is big league, this is a big-league case," Helfand told jurors, urging them to rid themselves of "preconceived" notions about it. He said that to most doctors, smothering simply means "the baby didn't get enough air, while to most people, smothering means someone did it."

Helfand told the jurors that prosecutors only brought the case at the urging of Garrett Michael's mother, Mary "Missy" Anastasi, and because of the insurance.

"They did it because he had insurance. It's the one thing that supplies a motive," Helfand said. "If you convict a man because of his motive, then so be it. But you won't do it because of scientific evidence."

Helfand said Wilson was at a disadvantage because he was unable to hire a pathologist to examine the children's bodies. Helfand also criticized the prosecution's expert witnesses as hired guns who would say anything they are paid to say.

Wilson sat in a dark gray pinstriped suit, sobbing at times during Helfand's opening statement. But he sat unmoved through Fennell's testimony, as photographs of both dead children were shown to the jurors and as the pictures of Brandi Jean's lime-green room were displayed.

Fennell, in emotional testimony that lasted more than an hour, told the court that she originally wanted no part in the case against Wilson but that it was only after she began talking with prosecutors that she learned about the insurance money her former husband had received after Brandi Jean's death.

She testified that several months after their child's death, Wilson brought home a new Pontiac Trans Am. They separated four months after Brandi Jean's death. "I had enough. I was tired," Fennell said.

Fennell told the court she first met Wilson in 1979, when she was 12 and singing in the choir of a Prince George's church, where Wilson, then 20, also sang in the choir and served as the congregation's youth director.

He showered her with attention and bought her expensive gifts, and by the year's end, she said, they were involved in a sexual relationship: "He started showing me attention, buying me things. He'd send me roses, drive fancy cars. . . . He'd take us bowling, and things just happened."

By 15, she told the court, she had had four abortions, all at the prodding of Wilson.

Brandi Jean was the result of her fifth pregnancy, Fennell testified.

After learning of her fifth pregnancy, Fennell, still in the 10th grade at Friendly High School, said she didn't want to tell Wilson about it. She mustered the boldness to do so, she said, and Wilson, her then-boyfriend, took her to another Maryland abortion clinic. "Garrett just decided that's what had to be done," she said.

The doctor refused, saying that because she was already five months pregnant, she would have to carry the baby to term. She had no choice but to tell her parents of her pregnancy. Fennell testified that she and Wilson married in October 1980 after she couldn't get an abortion.

Less than two months before Brandi Jean's birth, Wilson asked Fennell whether she would "be okay if anything happened to the baby. I couldn't say anything," Fennell told the court, tears filling her eyes as she clutched a white tissue. "I told my mom."

On the night that Brandi Jean died, Fennell testified, Wilson first called her parents, who in turn called paramedics. She said that she slept through everything and that she was awakened by her parents, who told her Brandi Jean was dead.

"I tried to get into Brandi's room. The police officer wouldn't let me in. So I stood outside her door, my daddy held me, and I cried," Fennell said as she rocked back and forth in the witness chair.

Jean and Kyle Oliver, Fennell's parents, are scheduled to testify today.