At Yates's trial, which is expected to last three weeks, one of the key issues for the defense may be explaining why, if Andrea was so sick and so overwhelmed, the couple kept having more children. One former neighbor, Sylvia Cole, suspects the answer may not be entirely flattering to Rusty. "He was adamant that they were going to have six kids,"says Cole, 45. "She was meek and easygoing, so I'm not sure if it was a joint decision." It was Rusty's belief that "the woman should do all the child care," Andrea's brother, chemist Andrew Kennedy, 46, told PEOPLE. "Andrea was the one who did all the diaper changing and everything." Still, says Kennedy, "she wanted to have those kids just as much as he did. So you just can't blame Rusty."

Certainly Rusty had long exuded considerable self-assurance. He and a younger brother, Randy, now 36, were raised in Hermitage, Tenn., a suburb of Nashville, where their father, Russell Sr., who died of a heart attack in 1981, worked as a salesman, while their mother, Dora, 63, taught school. At DuPont High School, Rusty lettered in football and graduated third in his class. He went on to Auburn University, where he further excelled in his studies, graduating in 1987 with highest honors and a degree in math. His academic record helped him get a job as a computer engineer at the Johnson Space Center. As a young bachelor in Houston, he didn't date much, spending much of his time on his own. "Rusty did his own thing," says friend Mike Ruiz, 44, who has worked with Yates for 12 years at NASA and once shared a house with him.

Andrea, too, was a high achiever. She grew up in Houston, the youngest of five children -- Andrew, now 46; Brian, 45, a self-employed electrical worker; Patrick, 44, the manager of a shipping company in El Toro, Calif.; and Michelle, 39, a dialysis nurse in Georgia. As it turns out, three of Andrea's siblings have been treated for depression. Their father, Andrew Kennedy, who had Alzheimer's and died last March at age 83, taught high school auto mechanics and was a "disciplinarian," Andrea later told a hospital staffer. He could be exceedingly demanding. "When she brought home a B, he asked why it wasn't an A," recalls Marlene Wark, 37, Andrea's best friend in high school. Her mother, Karin, 72, a former department store manager who still lives in Houston, was "supportive, sensitive, caring and nurturing," Andrea said in a hospital interview two years ago.