A suburban Chicago man is accused of setting an apartment fire — killing his pregnant daughter, her husband and their young child — because the son-in-law didn't ask permission for the marriage, prosecutors said.

Subhash Chander, 57, of Oak Forest was ordered held without bond Tuesday on three counts of first-degree murder, one count of intentional homicide of an unborn child and one count of aggravated arson.

Prosecutors allege Chander used gasoline to start the fire late Saturday. The India native told police he disliked his son-in-law because he belonged to a lower caste and had married his daughter without his consent, said Cook County First Assistant State's Attorney Robert Milan.

"His son-in-law was beneath him in his opinion," Milan said.

But Chander's sister, Kamla Devi, told WBBM-AM that her brother is innocent. She said that relatives approved of the marriage and that the caste system was not a consideration for her family in India, nor is it a consideration now in the United States.

"There was no family problem. There was nothing going on. Absolutely nothing," Devi said.

Devi told the radio station that the family is from Chandigarh in northern India.

The Cook County medical examiner's office said the victims died of carbon-monoxide poisoning and smoke and soot inhalation.

Milan identified the victims as 22-year-old Monika Rani, her 36-year-old husband, Rajesh Kumar, and their 3-year-old son, Vansh. Rani was five months pregnant, Milan said.

Chander had a public defender in bond court Tuesday, Milan said, but The Associated Press was unable to determine who it was. A call to a listing for Chander reached a man who said it was a wrong number.

Chander told police the gasoline spilled during "a pushing match" with his son-in-law, Milan said. Chander also told police that he ignited the gas with a lighter because he was angry, Milan said.

But prosecutors said the victims may have been asleep. All other residents of the apartment building were able to escape, Milan said.

It took firefighters three hours to extinguish the blaze, which gutted the 36-unit Le Claire Station Apartments.