(CBS) — An Oak Forest man has been sentenced to life in prison without parole for the 2007 arson deaths of his pregnant daughter, son-in-law and grandson.

Prosecutors said Subhash Chander was offended because his 22-year-old daughter, Monika Rani, had married without his consent, beneath her station in India’s caste system.

Prosecutors said they argued on and off for three years before he set fire to the apartment building at 15859S.Leclaire Ave., in which his daughters’ family lived, across the street from his home.

The blaze killed Rani, husband Rajesh Arora and three-year-old grandson Vansh Kumar and left 70 homeless.

Surveillance video showed Chander buying gasoline in a container two hours before the fire erupted. The gas station attendant was among those who picked Chander out of a lineup.