An 83-year-old woman and her daughter-in-law were robbed allegedly after being fed medicine and food laced with sedatives by a former help who came on a courtesy call and offered a hand, police said.

Sanju Sarkar and her husband Baidyanath Sarkar met the family saying they were nearby and wanted to say “hello”, a move that would not raise suspicion in most homes.

The family said they could not imagine that someone who had worked for them and quit only two months ago could poison them for money.

The accused couple have been arrested and charged with attempt to murder, theft, causing harm by feeding poison and criminal conspiracy. A part of the stolen money has been recovered, the police said.

The theft took place in a house on Sodepur Road in Haridevpur on Tuesday evening when college teacher Avijit Das was at work and his wife and mother were home.

“Sanju Sarkar had worked in the house in August and September. After that, she left. On Tuesday, she and her husband went to the Das house on the pretext of a courtesy visit and offered to help the women take their medicines and food,” said an officer at Haridevpur police station.

The police said the women passed out after consuming what they were given.

A relative said Sanju offered medicine to the 83-year-old woman and a health drink to the other woman, after which they lost consciousness.

Avijit Das’s sister Anindita, who lives in the same neighbourhood, said: “She (Sanju) came to our house around 4.30pm and used my sister-in-law’s phone to call my brother asking when he would return home. My brother said it would take him an hour.”

Around 5pm, Anindita Das saw the family’s cook standing near the entrance to her brother’s house and, on enquiring, the cook said both women were lying unconscious inside.

“I went inside and found my mother unconscious and my sister-in-law barely conscious,” Anindita said.

By the time Avijit returned, he figured out that Sanju had visited their home as she had called him to enquire when he would return.Sometime later, he discovered that ₹4 lakh was missing from the cupboard and his wife’s gold jewellery was gone. The police were informed.

The deputy commissioner (south-west) of Kolkata Police, Rahul De, said:

“We have recovered ₹2 lakh from the house of the accused. An investigation is on to recover the remaining booty.”

An almost similar theft was reported on Sunday in Salt Lake, where an elderly woman was robbed of her valuables after she was administered an injection by the male nurse of her deceased husband.

A city where a large number of residents are elderly, who stay alone as their children have settled in other cities, has witnessed many such attacks.

Last November, an elderly woman who lived alone in her flat in an apartment in Charu Market was attacked. Later, the family’s driver was arrested.

Last September, a woman working as a caregiver to a 79-year-old woman in Salt Lake was arrested on charges of murder, 11 days after the woman passed away.

CCTV footage found by the elderly woman’s family revealed that the caregiver was in the habit of assaulting her.