The letter alarmed Marion because its content made her believe that Oxley had lost his mind. She left for Peru to care for him but when she arrived there she was captured by Soviet Special Forces who also had Oxley in their custody.
Shortly before he was captured by the Soviets, Oxley had written a second letter, but in a cryptic code. He passed this letter to Marion, and the Soviets let her escape just long enough to forward that letter, together with a letter of her own, to her son Mutt Williams, urging him to forward it to Indiana Jones.
Behind the scenes
Oxley's First Letter was not shown in the movie itself, but only mentioned by Mutt. No specific prop was prepared for this letter which, except for his content, appears to have been quite a normal letter.
- Indiana Jones and the Kingdom of the Crystal Skull (Mentioned only)