Part 2

From the text:

First, while sorting Nancy's clothes, Mrs. Elaine Selsor, her aunt, had found tucked in the toe of a shoe a gold wristwatch. Second, accompanied by a K. B. I. agent, Mrs. Helm had explored every room at River Valley Farm, toured the house in the expectation that she might notice something awry or absent, and she had. It happened in Kenyon's room. Mrs. Helm looked and looked, paced round and round the room with pursed lips, touching this and that - Kenyon's old baseball mitt, Kenyon's mud-spattered work boots, his pathetic abandoned spectacles. All the while she kept whispering, "Something here is wrong, I feel it, I know it, but I don't know what it is." And then she did know. "It's the radio! Where is Kenyon's little radio?"

Taken together, these discoveries forced Dewey to consider again the possibility of "plain robbery" as a motive. Surely that watch had not tumbled into Nancy's shoe by accident? She must, lying there in the dark, have heard sounds - footfalls, perhaps voices - that led her to suppose thieves were in the house, and so believing must have hurriedly hidden the watch, a gift from her father that she treasured. As for the radio, a gray portable made by Zenith - no doubt about it, the radio was gone. All the same, Dewey could not accept the theory that the family had been slaughtered for paltry profit - "a few dollars and a radio."