Treasury Agent Frank Wilson and Anne Morrow Lindbergh, that is.
The account below is taken from "Under Cover Man: Inside the Lindbergh Kidnaping." Collier's, May 19, 1947.
It also appears in the book Special Agent: A Quarter Century with the Treasury Department and the Secret Service. New York: Rinehart and Winston, 1965.
The Collier's Magazine article is a second in a series, and states that Wilson, a "Former Chief of the U.S. Secret Service tells of his part in the famous case...as told to Howard Whitman."
"One day I had lunch with [Anne] at Hopewell. She toyed with food intent only on telling me more and more details that might solve the crime. The question of the nursery window came up. Was it locked? No. Just how much was it open?"
"Mrs. Lindbergh said, "Come up to the nursery with me. I want to show you how the window was."
"I followed her into the nursery. The crib, which Colonel Lindbergh had shown me on my first visit, was gone. All the baby's toys were gone. As she walked toward the window I saw her eye dart for an unconscious moment to the corner where the crib had stood. Then she set the window just as it had been the night of March 1st."
"We walked through an adjoining bedroom. My eyes roved to the the walls and I stopped short. Mrs. Lindbergh passed at the door and watched me as I studied the flowered wallpaper. There was something strange about it. I couldn't tell just what it was at first. Then I noticed that on one side of the room the wallpaper had flowers with brightly colored centers; on the rest of the wallpaper the centers of the flowers were plain."
"Oh, that" said Mrs. Lindbergh. "I've been touching up the center of the flowers--I haven't finished yet. It's comforting to have something to do."
"I think that, more than anything, made me realize the battle she was putting up."