Drugged by the “salesgirl” who robbed her apartment six days ago, an elderly woman never recovered from the effects of heavy sedation and died on Wednesday morning.

Usha Banerjea, a widow in her mid-70s, used to share the house with elder sister Sushma Niyogi, who was drugged too and remains under observation in the same hospital where her sibling died.

The person responsible for the robbery — Rs 10 lakh worth of jewellery was found missing from a cupboard — and Usha’s death had visited the sisters’ third-floor apartment on Manoharpukur Road, under Lake police station, on April 25 in the guise of a door-to-door salesgirl hawking fruit juice, pickles and mustard sauce.

The sisters made the mistake of allowing someone they did not know to enter their living room and sit on the couch.

“The girl had noticed that the sisters were underweight. She advised them to buy a bottle of squash, claiming it would energise them. When the duo refused, she asked them to sample the squash in front of her,” a police officer said.

That is when Usha and Sushma made their second mistake. “The elderly women relented and became unconscious on consuming the drink. It was the moment the robber girl was waiting for,” the officer said.

The sedative used to spike the drink was so powerful that Usha and Sushma, 82, lay unconscious in their living room till the next day.

“Neighbours noticed that the door of the apartment was locked (the salesgirl had pulled the door shut) and that none of the sisters was seen throughout the day. They suspected something was wrong and informed the police. We broke open the door and found the two women lying there,” the officer said.

Admitted to the Ramakrishna Mission Seva Pratishthan, Usha did not respond to treatment for three days. She opened her eyes on Tuesday but could not speak. Her condition deteriorated as the day progressed and she died in the early hours of Wednesday.

Sushma, who briefly regained consciousness in hospital, narrated the sequence of events to the police but could not describe the robber girl's appearance.

A spinster, she is still in shock. “Although doctors have said her condition is stable, she cannot recall what happened on that day,” Rajesh Subarna, the deputy commissioner of police (south division), said.

“We have spoken to the other residents of the building, thinking the culprit might have attempted to enter their apartments, too. But they failed to provide us leads,” the officer said.