Complex sentence: Jim asks Mimi to turn herself in and confirm his alibi, for the sake of his daughter, Isabel; he doesn't want to leave Isabel behind and repeat the mistake that he and Mimi made 30 years earlier by giving up their own daughter.
Split into simpler sentences: Jim asks Mimi to turn herself in and confirm his alibi, for the sake of his daughter, Isabel. He doesn't want to leave Isabel behind and repeat the mistake that he and Mimi made 30 years earlier by giving up their own daughter.