In the end, the Mexican authorities said Friday night that Mr. Guzmán had been caught partly because he had been planning a movie about his life, and had contacted actors and producers, which had helped the authorities to track him down. Mr. Penn’s story says that Mr. Guzmán, inundated with Hollywood offers while in prison, had indeed elected to make his own movie. Ms. del Castillo, whom he contacted through his lawyer after she posted supportive messages on Twitter, was the only person he trusted to shepherd the project, according to the story. Mr. Penn heard about the connection with Ms. del Castillo through a mutual acquaintance, and asked if he might do an interview.