The Research and Analysis Wing started trailing diplomat Madhuri Gupta and listening to her phone calls after one of its officials in the Indian High Commission in Islamabad reported her undue interest in certain matters that did not concern her responsibilities, sources said.
On Tuesday, the Delhi police confirmed the arrest of Gupta, a promotee officer of the ministry of external affairs, on the charge of passing strategic secrets to Pakistan.
The official, who became suspicious about her queries, may also face music for allegedly providing her certain sensitive information that she may have passed on to her Pakistani contacts. An explanation has been sought from him and he has been told to disclose the information that he had shared with the lady, said sources.
Gupta has been working for the external affairs ministry for almost three decades and her responsibilities in Islamabad included liaison with other embassies.
A joint team of RAW, the Intelligence Bureau and sleuths of the Delhi police's special cell are interrogating her to ascertain whether she had any accomplices who also worked for Pakistan during her posting in Islamabad. They are trying to bust any spy ring that Pakistan could have created within the Indian High Commission.
Sources said Gupta had been under RAW's surveillance for the past six months in Islamabad and the external affairs ministry was asked to call her to Delhi last week on the pretext of her being required at the South Asian Association For Regional Cooperation summit in Bhutan as an Urdu interpreter.
Though the police claims that she was arrested from her east Delhi residence on Sunday, sources said that Gupta was nabbed as soon as she arrived at the Delhi airport on Friday. She was accosted by intelligence officials, who detained and grilled her for two days, before the special cell of the Delhi police was called in to book her.
She was taken to her residence, which was thoroughly searched before the police formally arrested her on Sunday night. The police seized seven incriminating documents and two mobile phones, one with an Indian sim card and another with a Pakistani sim card. Her phone calls were being monitored for some time.
Sources said Gupta is being interrogated about the money she has been depositing in a Pakistan bank and then transferring to India, as this was allegedly the regular pay-off she received from the Inter Services Intelligence.
As happens in cases under the Official Secrets Act, intelligence sources claimed that Gupta has confessed to spying for Pakistan, though inquiries show that the police did not mention any such confession made by her on Monday, when she was produced before a court in Delhi. The same sources even claimed that she compromised India's national security because she was dissatisfied with her service conditions and needed money. The sources claimed that a large chunk of money she got from the ISI was still lying in a Pakistan bank.
The government has already ordered an inquiry in Delhi and Islamabad against all staffers posted in the Indian High Commission in the last three years for any possible spy ring operating from within. Their bank accounts are being checked to ascertain any unusual transactions, sources said.
A highly-placed official said though Gupta holds technical status as a diplomat, she is not from the Indian Foreign Service cadre. He protested against the media describing her as the first-ever Indian diplomat arrested for spying.
"She is a B-grade officer in the Urdu translation section of the foreign office and is posted in Islamabad as an Urdu interpreter," he said.
Gupta will be produced before the court again on Thursday for further extension of her remand, police sources said. She has been booked under sections 1A and 2A of the OSA that carry a maximum punishment of 10 years.