A man is found hanged from a showerhead in a prison cell. He leaves behind a suicide note confessing to a separate murder. FBI investigators conclude the death was staged. They cite three specific findings. Two are physical: the man was too tall to hang from the showerhead, and the showerhead was too flimsy to support his weight. The third finding is documentary. What was the documentary finding, and why does it — rather than either physical finding — most conclusively prove the death was staged?