Mohan Charegaonkar, a priest, and his son Vinayak (21) took the extreme step by hanging themselves from a rafter on May 5 at their house, an official attached to Gandhinagar police station said.
May 5 also happened to be the first death anniversary of Mohan's wife Vandana, the official said.
A case under relevant sections of IPC has been registered and investigations are underway, police said.