A Montgomery County jury yesterday convicted Garrett Eldred Wilson of murdering his 5-month-old son 12 years ago in a death that originally was attributed to Sudden Infant Death Syndrome.

The eight-man, four-woman jury spent just over two hours deliberating the fate of Wilson, a former piano salesman who was accused of smothering his son and an infant daughter six years earlier to collect $190,000 in life insurance money.

His trial was the latest in a series of murder prosecutions across the country arising from infant deaths that had been attributed to SIDS.

Wilson, 43, faces a September trial in Prince George's County on a first-degree murder charge in the 1981 death of his 2-month-old daughter, Brandi Jean Wilson. Circuit Court Judge Ann S. Harrington ordered him to be held without bond at the Montgomery County Detention Center until he can be sentenced Sept. 3.

Prosecutors have asked Harrington to sentence the Frostburg, Md., man to life in prison without parole. Defense attorney Barry H. Helfand said that he expects the sentencing "will not be lenient" and that he hopes Wilson will "live to fight another day."

Helfand described Wilson as shaken and said the man sat heaving, "almost like someone hit you in the stomach and took your breath away."

Much of the case against Wilson relied on evidence gleaned not from the 1987 death of his son, Garrett Michael, but from the death of Brandi Jean in 1981. Harrington ruled that jurors should be permitted to hear information about the earlier death because of overwhelming similarities between the two cases.

Medical examiners initially attributed both deaths to SIDS and ruled the manner of deaths natural.

But in 1997, the state's top medical examiner, John Smialek, reopened the case after new questions arose about the infants' deaths and with the benefit of a heightened scientific understanding of SIDS.

He ultimately changed the cause of Brandi Jean's death to smothering and ruled her manner of death "undetermined." Smialek also decided to change the cause of Garrett Michael's death to smothering and ruled that the manner of death was homicide.

Police were first alerted to suspicions about the deaths in July 1994, after Mary "Missy" Anastasi told them she had long feared that her former husband had killed their son.

Anastasi testified last week that in the predawn hours of Aug. 22, 1987, Wilson heard their son crying from his crib in another room. Anastasi said her husband rose to feed the infant in the middle of the night, something he had never done before.

Through a baby monitor, Anastasi said, she could hear Wilson rocking his son in a chair, then what sounded like the father putting the baby to rest in his crib. She heard a sigh but went downstairs to feed the family's restless cats.

After returning to the second floor, she said, she noticed her husband wasn't in the baby's room, but found Garrett Michael lying face-down in his crib.

Something didn't feel right, she told the court last week. She said the baby felt limp. She picked him up and ran into her bedroom, demanding of her husband, "What did you do to him?"

Anastasi phoned police, and two hours later, she learned that her son was dead.

From the day she met Wilson, she said, she had been aware that Brandi Jean, his daughter from a previous marriage, had died of SIDS. She so feared that her child, too, would die of SIDS that she sought genetic counseling.

Sitting in the Rockville courtroom's second row in a dark black suit, Anastasi held the left hand of her brother, Frank. As the jury's foreman delivered the verdict, her face turned red, and her teary eyes remained locked on her former husband.

Wilson, meanwhile, looked only at the foreman, and for at least the second time since the trial's start, it seemed as if he were about to cry.

Helfand attempted to portray Anastasi as a scorned woman who turned to police after learning that her husband had secretly divorced her after marrying another woman and having a daughter.

But Linda Norton, a Dallas-based forensic expert who is considered among the leading experts on SIDS, pointed to the autopsy's finding that Garrett Michael's brain was swollen at the time of death--a rare occurrence in SIDS cases, she said.

John P. Kokes, the medical examiner who performed the 1987 autopsy on Garrett Michael, estimated during testimony for the prosecution Monday that the probability of two children in the same family dying of SIDS--with one child's brain swollen--is 1 in 100 million.