A teenager who reportedly gambled online has been accused of murdering his parents, his younger sister and grandmother and burying their bodies in a trench on the premises of their home in Malda in February.

Asif Mohammad, 19-year-old suspect, stayed in the house alone for nearly four months since the February 28 murder at Gurutola village that falls under Kaliachak police station in Malda, police sources said on the basis of preliminary investigations.

The crime came to light and Asif was arrested after his elder brother Arif informed the police of the murders on Friday night.

Arif, 21, claimed that his brother wanted to kill him, too, but he could somehow escape. Arif said he had been staying all this while in Calcutta. It is not clear where he was staying in Calcutta.

The crowd near the site of the murders. Soumya De Sarkar

The police are verifying the account of Arif. “It is surprising that Arif was silent for four months, despite knowing that his brother Asif had killed four family members,” said a police officer.

On Saturday, the police raided the house to recover the skeletal remains of their parents Jawad Ali, 53, and Ira Bibi, 39, sister Rima Khatun, 16, and grandmother Aleknoor Bewa, 73.

Jawad Ali, a relatively wealthy trader, also had several godowns. The family was better off than the neighbours and did not interact much with residents in the area, one of the reasons the murders remained undetected for months.

“Preliminary investigations suggest that on February 28, Asif had offered cold drinks laced with some strong tranquilliser to all the four. As they became senseless, he tied up their limbs and put leucoplast on their lips. All the four were choked to death. He had dug a trench in the house where he buried the bodies,” said Alok Rajoria, the superintendent of police of Malda.

“Arif, his elder brother who has informed us of the crime, has said that Asif also tried to kill him but he escaped,” Rajoria added.

Since then, Asif had been staying at home alone. He had fitted CCTV cameras around the house to keep a watch on neighbours.

“We have come to know that he is a hacker and he gambled online…. There are suggestions that he used to mount pressure on his parents for big sums of money. It might be one of the motives for the murders,” said a police officer.

In Gurutola, hundreds of onlookers swarmed around the house as the police brought the brothers to the site.

In the presence of an executive magistrate, the bodies were dug out of the trench.

Police sources said that Arif, who claimed to be in Calcutta, had come to know that Asif was planning to sell the house. Arif met some relatives on Friday night and narrated the incident to them.

Some of the relatives took him to the police station where he recounted the alleged events of February 28.

The police then picked up Asif.

During the raid, the police have found over Rs 1 lakh in cash and a number of electronic gadgets in the house.

Shocked villagers said Asif’s activities had aroused their suspicion.

“We couldn’t see any other member of the family for months. Also, Asif would scrupulously avoid us. He would order his food online. Whenever anyone asked him about the whereabouts of his parents and other family members, Asif used to say that they were away in Calcutta,” said Noushad Ali, a villager. “He gave us the impression that they would all settle in Calcutta.”

Rajoria, the district police chief, said the bodies have been sent for autopsy.

“We have arrested Asif and are questioning Arif,” he said.

Police officers saw some similarities with another crime that came to be known as the “Bhopal” killer case.

Udayan Das had murdered his girlfriend in Bhopal in 2016, buried her body in

the house and made a tomb. After he was arrested, Das had confessed that earlier, he had murdered his parents, too, and had buried their

bodies at the lawn of their house in Raipur, Chhattisgarh, where they used to stay earlier.

Das was sentenced to life imprisonment last year.