. >> pelley: today, pope francis went to the heart of mexico's drug war and challenged priests to fight injustice, violence, and corruption. this comes at the same time of a fascinating revelation about pope john paul ii. private letter rez veal a close friendship with a woman that lasting for decades. >> reporter: he was then a young polish cardinal. she was a polish american writer and married. yet, when karol wojtyla, the man who would become pope john paul ii, began to collaborate with anna teresa tymieniecka on a a book happened. they wrote to each other for the rest of their lives, his letters recreated in a bbc documentary. their relationship would test the cardinal's vow of celibacy. particularly, he says, the words, "i belong to you." malina malinovsky brokered the sale of the letters to the polish national archive. >> i do believe she completely fell in love with him during the first phase of their relationship. >> reporter: they didn't just write. they spent private times vermont, skiing in poland. in the old communist days when she was in krakov, she had her letters hand del
