Policemen at the Dhars’ flat in Kasba on Thursday night. A Telegraph picture

Swati Dhar, who allegedly throttled her five-year-old son before hanging herself on Thursday night, had been suffering from depression and was being treated by a psychiatrist.

Police suspect husband Dhritimay’s busy schedule — he had been at the Swinhoe Lane flat in Kasba for hardly three months in the past year — drove the 28-year-old to depression.

“We do not suspect any foul play,” said D.P. Singh, the additional superintendent of police (industrial), South 24-Parganas. “A case has been started on the basis of a complaint lodged by Ratan Hazra, a resident of the apartment block. Hazra, along with Dhritimay, was the first to see the bodies.”

Soon after encountering the shocking sight, Dhritimay took son Riddhi to hospital, where the child was declared dead on arrival. The police later brought down Swati’s body.

“Though the woman’s family has not lodged any complaint against Dhritimay, a senior official of a private pharmaceutical company, he will be questioned after he recovers from the shock,” said an investigating officer.

A brother of Swati has given the police a statement, saying he did not hold Dhritimay responsible for the tragedy.

The sleuths on Friday found some prescriptions in the third-floor flat, which suggest Swati was under medication for depression.

“We have also come across some of her writings, through which Swati had expressed her ‘deep love’ for her husband. She had expressed no anger or resentment against anyone. She had also made a list of her assets, like ornaments, bonds and bank papers,” the officer said.

Dhritimay, from Canning, and Swati, from Baruipur, knew each other from their school days. “Theirs was a marriage for love. The neighbours told us the couple mostly kept to themselves. Swati, in particular, was an absolute introvert,” said an officer.