It Had to Be You — Jill Churchill

Comfortably ensconced in their late great-uncle's "Grace and Favor" mansion, brother and sister Robert and Lily Brewster are riding out the Depression, penniless but in high style. Now a new day is heralded by Franklin Roosevelt's inauguration. Barely recovered from his trip to Washington to witness the historic event, Robert is rushed by Lily to a nearby nursing home, where the Brewsters have agreed to lend a helping hand to the staff.

But when an elderly resident is murdered in his bed, Robert and Lily realize the local police will need their able assistance as well -- especially since the slaying isn't the only big trouble in tiny Voorburg. The spring thaw has revealed another body, and the Brewster siblings must expose a cold-blooded criminal before he -- or she -- kills again.