The dead couple. (PTI)

Chandigarh, Sept. 3: Mystery surrounds the death of a young couple and their two children in a Santro car fitted with a central locking system on the Faridabad-Delhi highway.

“While the initial post-mortem reports indicate death by suffocation, we have expanded our investigation to probe all angles, including murder,” a Faridabad police officer said over phone.

Dhanesh, his wife Ruhi, son Ayush, 4, and daughter Kritika, 2, were returning home after a dinner at a friend’s place around 8.30 last night when they ran into a waterlogged stretch following heavy rain in the region.

“It is not clear yet whether the car stalled due to the rain and the water on the road. But the air-conditioner blower was switched on. All four had blood oozing from their mouths,” the officer said.

This morning, a local resident informed police about a car with four unconscious people. The police had to break open the window-panes to pull the bodies out.

“There was some mud inside the car, indicating that the occupants may have opened the doors to get out and then get back in as there was no shelter nearby,” the officer said.

Faridabad police chief Mahender Singh said the family could have died due to depletion of oxygen. “Some poisonous gas could also have emanated from the car that could have led to their deaths,” he said. “We are checking with experts if the car’s central locking system had failed.”

Relatives of Dhanesh have demanded a probe. “There was blood on their mouths. The car was also not parked on the side. How is it that no one noticed the bodies till morning?” a relative asked.

Others said if the vehicle’s central locking system failed, Dhanesh could have used the horn to attract attention of people living nearby or tried to break open the window-panes.

The police have questioned the friend in whose house Dhanesh and his family had dinner.

“We will wait till the final post-mortem reports arrive. Whatever the cause of death, we would like everyone having cars with central locking systems to keep some equipment within easy reach that can be used to break the panes in case the system fails,” an officer said.