Police say the 50 year-old was killed by a younger man at remote Rakisu Village in Tikopia last week.
A 30 year-old suspect accused the victim of using sorcery to kill his child and poison his wife.
Police commissioner Mostyn Mangau said witnesses alerted by the victims' cries for help saw the accused fleeing the scene
They took the victim of the attack to a local clinic where he died from acute blood loss, before being buried last Saturday.
Commissioner Mangau said he died the victim also made a statement which was recorded on a phone.