The victim, identified as Nadia Fatun (28), was declared brought dead at a city hospital on Saturday.
The victim and and her husband Jia-ur Rehman (32), a Lance Naik, who was recently transferred to Tamil Nadu, had arrived at the Chhatrapati Shivaji Terminus (CST) on Friday.
The couple, who hailed from West Bengal, had come to Mumbai and booked a retiring room after their arrival at CST.
However, after some time, the duo felt uneasy and asked the attendant to shift them into another room. The couple was then accommodated in the officer's room. They stayed there overnight, but the following morning they suffered from giddiness and started vomiting.
"The couple felt unconscious in the afternoon. The attendant brought the matter to the notice of deputy station master and the couple was rushed to a nearby hospital. However, the woman was declared brought dead on arrival, while the jawan is under treatment," police said.
After learning about this development, state Forensic Science Laboratory (FSL) teams were called in yesterday. They collected samples from walls, furniture and others to check if it is a case of residual air poisoning, caused by wrong or excessive pesticide, police said.
"According to doctors it could be either food poisoning or inhalation of insecticide," the officer added.
Further investigation into the case is on.
