Chandra Pal Singh, a retired soldier, and Sauraj were found dead in Badgaon in Saharanpur district Oct 2.
Police earlier thought the killings were related to the communal riots in Muzaffarnagar and nearby areas that left 63 people dead Sep 6-10.
But investigation revealed that Jogendra, the younger son of the soldier, shot his father so that he can claim the Rs.10 lakh in compensation and Rs.15 lakh from his insurance.
Jogendra and his widowed mother claimed that men from a neighbouring village killed Chandra Pal Singh.
Officials told IANS that to give the crime a communal angle, the accused had thrown in a skull cap at the crime scene.