The victim, Yaseen, was beaten to death when he had gone to their house yesterday to question them about the alleged harassment of his daughter, they said.
His sons, Imtiyaz and Mumtaz, were also beaten up by the accused, police said.
A case has been registered against six persons, including the son-in-law Zakir, his father Mosemali, mother Wakila, brother Asif, they said.
Efforts are on to arrest the accused who are absconding, police said.