Metiabruz: A 15-month-old infant playing with his twin sister drowned in a bucketful of water on Sunday evening after crawling into a washroom unnoticed when their parents and elder brother were in an adjoining bedroom.

Rajgopal Behera was dead by the time his parents found out what had happened and rushed him to a nearby nursing home. "The door from the dining room to the washroom was open and nobody in the family knows when Rajgopal climbed into the bucket," said Jyotsna Rai, the twins' aunt.

Their father Narayan Behera realised something was amiss only when he saw the other twin, Mona, playing alone. "He searched the apartment but the boy wasn't in any of the rooms. He entered the washroom and saw Rajgopal's tiny legs peeking out of the bucketful of water," Jyotsna said.

She could not say how much time had passed before Rajgopal was found. "All we know is that Narayan noticed Mona was alone at least 15 minutes after he had seen the twins playing."

Narayan, who works for Garden Reach Shipbuilders & Engineers Ltd, and his wife had been helping their elder son Nandogopal with his studies when tragedy struck.

The family had approached several doctors for a death certificate but none agreed to write one. Neighbours of the family informed the police about the incident. The doctor who conducted the post-mortem at SSKM Hospital told the police that no external injury mark was found on the body. "We have not received any complaint of foul play yet. A case of unnatural death has been registered," a police officer said.

The Beheras, whose roots are in Odisha, have been living in a two-bedroom flat on the third floor of a building in Metiabruz for three years.