What is the ruling on someone who created a page on the internet to defame a girl and her family, and this led to the death of her father? Is his act considered involuntary manslaughter? What must he do to repent, and what should the villagers do if he persists in his actions?

Slander (buhtan) is a grave sin and a clear transgression. It is speaking about your brother that which is not in him, as the Prophet, peace and blessings be upon him, said: "If what you said about him is true, then you have backbitten him; but if it is not true, then you have slandered him." It is considered one of the major sins, for Allah the Almighty says: "And whoever commits a sin or a wrongdoing and then throws [the blame] upon an innocent person has certainly borne slander and a clear sin" (Quran 4:112). The Prophet, peace and blessings be upon him, also said: "Whoever says something about a believer that is not in him, Allah will make him dwell in the mire of corruption (radghat al-khabal) until he recants what he said." If the slander involves accusing someone of committing indecency, then it is qadhf (false accusation of unchastity), which incurs the curse, and it is among the seven destructive sins.