The kidnapping and death of American aviator hero Charles Lindbergh's infant son in 1932 was labeled the "Crime of the Century." A hand-made wooden ladder left at the scene provided some of the most critical evidence that connected Hauptmann to the crime. The evidence analysis was done by Arthur Koehler, wood technologist for the U.S. Forest Service, who performed meticulously detailed studies to provide three lines of plant anatomical evidence crucial to Hauptmann's conviction and subsequent execution. Koehler traced part of the ladder's wood from its mill source to a lumberyard near the kidnapper's home through faint machine planing marks even before the suspect was known. After Hauptmann's arrest, Koehler demonstrated by wood anatomical comparisons that one of the side rails of the ladder previously had been part of a floorboard in Hauptmann's attic. Finally, he established that Hauptmann's hand plane had been used to dress the edges of several ladder parts. Koehler's testimony at trial was a turning point in the acceptance of botanical evidence as expert scientific evidence in the courts. 13 figures and 37 references