Start with the victims. What kind of family is the Clutter household? In what way does Capote create sympathy for them?

The reader is introduced to the village of Holcomb, a small yet prosperous farming settlement in western Kansas. Herbert Clutter, a self-made man and prominent member of the community, lives a comfortable life as the owner and proprietor of River Valley Farm, where he resides with his wife, Bonnie, and children, Nancy (sixteen), and Kenyon (fifteen). The Clutters are a principled and upstanding family, active churchgoers and participants in community life, both in Holcomb and the neighboring Garden City.

Nancy, who is a “straight-A student, the president of her class, a leader in the 4-H program and the Young Methodists league, a skilled rider, an excellent musician, and an annual winner at the county fair,” also volunteers her time to instruct younger girls in baking and other domestic occupations, and has recently played a principal role in the school production of “Tom Sawyer.” Kenyon, more reticent than his sister, spends much of his time woodworking in the Clutters’ basement shop, or hunting rabbits with his best friend Bob Jones. The Clutters’ peaceful and contented existence is marred only by the fact that Bonnie Clutter suffers from clinical depression, a condition that leaves her bedridden on many days; however, doctors have finally traced her ailment to dislocation in her spinal column, and she is expected to make a full recovery.

The Clutters are a "normal" family. They are hardworking, popular, and well-liked in the town. These are nice people and that, in itself, creates sympathy for the family.