D.B. Cooper

In Morris, Christiansen was waiting.

He is 77 years old, retired from the post office, and now works as an inventor and holds a few patents. Every day, he’d walk out to his mailbox hoping for a reply from Ephron. Nothing came. He sent Sherlock another letter, which Porteous had delivered. Weeks passed. No word. Did she know he was paying all this money to reach her? Finally, Christiansen wrote to Sherlock: “As you know, I have been trying to contact Nora Ephron, but for some reason she doesn’t answer my letters. Now I would like you to help me. I am sitting on the answer to a many decades mystery which has never been solved … No one was killed or injured in the caper but could easily have been … I hope you will think about this and let me know.”

Porteous was curious. He began to probe with e-mails. Christiansen would often type back late at night, he said, so his wife wouldn’t discover his secret relationship with D.B. Cooper. “Yes, I knew the culprit personally,” Lyle wrote one day. “He was my brother.”