The victim was an older woman, a widow of more than 20 years. She left behind a sizeable estate — more than $6 million in cash, property, and investments. Two grown sons survived her, both now in their 60s. One daughter-in-law. No grandchildren. No brothers or sisters. Not a large circle of friends. No obvious enemies, either. Robbery had not been the motive. The only item unaccounted for in the house: a boning knife missing from the Wusthof cutlery set on the kitchen countertop.