Jessica Lynne Carpenter was 14 years old on Aug. 23, 2000, the morning 27-year-old Jonathan David Bruce came calling at the Carpenter house in Merced, Calif. Jessica Lynne knew how to shoot -- her father had taught her. And there were adequate firearms in the house to deal with what happened next. That Wednesday morning, Jessica was home with four of her siblings -- Anna, 13; Vanessa, 11; Ashley, 9; and John William, 7 -- in the San Joaquin Valley farming community, 130 miles southeast of San Francisco. Bruce, an out-of-work telemarketer apparently high on drugs,