Question: A weak man is now 60 years old, and he remembers that he committed a major sin when he was less than 20 years of age. He had sex with a she-donkey during the daytime in Ramadaan 36 years ago. He asked for a private Fatwaa (legal opinion issued by a qualified Muslim scholar) about his act. We cannot give him the answeror give him Fatwaa. We hope that Allaah (Exalted be He) will help you give us Fatwaa in this regard. We also ask you to reply to us in a written letter. We supplicate to Allaah, the All-High and Omnipotent to multiply your reward and to accept our repentance and that of all Muslims, for He is the Best Guardian and the Supporter.
Answer: This man is required to make up for the day in which he did it, feed a poor person for delaying making up for that day, and repent to Allaah (Exalted be He) for what he did… read more here.