Because of its sensitivity, for the first two years, the couple refused to divulge the subject of their first book to their children. ''We just said it's about a bad lady,'' Ms. Talan said she told their twin girls, now aged 9, and 6-year-old son.

The book originated in 1994 when Mr. Firstman heard on the radio, while driving to work, about the arrest of Waneta Hoyt, a woman in upstate New York who was convicted, 25 years after the fact, of murdering her five children. A district attorney had become suspicious about the deaths, diagnosed at the time as due to SIDS, when he read about the cases in the journal Pediatrics.

Mr. Firstman dashed for his wife's desk and told her, ''I think there's a book here for us.'' He recalls thinking, ''What a perfect collaboration, with the medical and legal aspects that played to both our strengths.'' Mr. Firstman continued, ''We set out to write a book about a really fascinating murder case. The more we got into it, we saw there was a more important story....'' ''About science,'' Ms. Talan finished his sentence.

The book describes how a medical researcher in Syracuse, Dr. Alfred Steinschneider, treated two of the Hoyt babies and, unaware that they were smothered by their mother, based his theory of SIDS on these cases. ''Dr. Steinschneider wanted a theory very badly and became blinded to what nurses were telling him and what the data showed,'' Ms. Talan said.

Dr. Steinschneider's 1972 medical paper convinced the pediatric establishment that SIDS was related to apnea, a temporary cessation of breathing. His claims led to a thriving industry in apnea monitors, an expensive apparatus that sounds an alarm when a baby hooked up to its wires breathes irregularly. ''The impact of that paper is still immense today,'' Mr. Firstman said.

Indeed, 40,000 babies are now on home apnea monitors, ''for no real medical reason,'' said Mr. Firstman. In an editorial in the October issue of Pediatrics, Dr. Lucey wrote, ''This month marks the 25th anniversary of the now infamous article by Dr. Steinschneider. We never should have published this article. When an unsupported hypothesis attracts support from parents, government and becomes 'a religion,' it's impossible to stop. In fact, monitoring is still going on and some physicians still believe SIDS runs in families. It doesn't -- murder does.''

The Steinschneider paper detailing the five Hoyt children's deaths led to the erroneous belief that SIDS is hereditary. Only recently has the maxim become accepted in forensic pathology: ''One unexplained infant death in a family is SIDS. Two is very suspicious. Three is homicide.''