Must the questioner's friend fast two consecutive months as expiation for accidental killing, after he struck a man with his car, who was consequently admitted to the hospital and died three days after the accident due to anesthesia complications for a disease he was suffering from?

If the victim remains affected by the pain of the injury until death, then the perpetrator owes expiation (kaffara), and his 'aqila (male relatives on the father's side) owe the blood money (diya). However, if trustworthy doctors determine that the cause of death was the effect of anesthesia, and that the injury was minor and could not have led to death, then the friend (perpetrator) is not liable for expiation or blood money, except for the blood money for the impact injury itself. But if the doctors determine that the cause of death was the accident, then its consequences follow, and the perpetrator is liable for expiation (freeing a slave or fasting for two consecutive months), and his 'aqila are liable for paying the blood money to the heirs of the deceased if they demand it. If they pardon, then only expiation is incumbent upon the perpetrator.