Robin Murmu axed his father, Sukhram and mother, Nilmoni to death at Burisolse village, Bandwan BDO Madhusudan Mondal said.
Robin's wife had fallen ill frequently and had died later, he said.
Robin suspected that his wife had fallen ill anddied because of witchcraft practised by his father and mother, he said.
The son surrendered to the Bandwan police station after committing the crime, he said.