Megh Raj was beaten to death and his wife Kawita and son Rajesh were injured after they were attacked by the victim's brother yesterday, they said.
Lekh Raj attacked the family over their objection to a wall construction, they said.
A case has been filed, police said, adding the accused is absconding.
In another incident, one Roshan was stoned to death by his brother Rohtash over a minor dispute involving collection of water from the latter's hand pump, police said.
The incident took place at Kasoli village in the district yesterday, they said.