An employee of Calcutta High Court and his friend were arrested on Thursday on the charge of raping a 23-old-woman and blackmailing her.

Ambar Kanjilal, who works in the office of the registrar of the high court, and his childhood friend Suvro Sen raped the woman in her house on May 16 after offering her food laced with sedative, said South 24-Parganas police superintendent Ajey Ranade.

They also took some obscene photographs of her and kept threatening her to do their bidding.

Ambar was the victim’s private tutor when she was in college.

“The duo have been slapped with charges under IPC sections 376(2)(G) [gangrape], 506 Part II (criminal intimidation), 509 (gesture or act intending to insult the modesty of a woman) and 328 (causing hurt by means of poison, etc. with an intention to commit an offence),” said Anirban Guha Thakurta, the woman’s lawyer. They will be produced in court on Friday.

The police said Ambar, 32, developed a relationship with the woman in 2005, when she was studying commerce in a south Calcutta college.

“The woman stated in her complaint that Ambar had proposed to marry her in 2006. But their relationship soured soon after when Ambar insisted on physical intimacy,” said an officer investigating the case.

The woman considered walking out on Ambar but changed her mind when he threatened to commit suicide. “She later realised that the suicide threat was a ruse,” the officer added.

On May 16, Ambar and Suvro, who works in a private firm, went to the woman’s house when she was alone.

“The three chatted for a while before the woman left to make tea. When she rejoined the duo, Ambar offered her samosas. The woman fell unconscious after eating one or two samosas. The duo then raped her repeatedly and took several obscene photographs of her,” the investigating officer said.

When she came to she found the duo had left.

According to the complaint, Ambar started threatening the woman from the next day that he would circulate the photographs among her friends and relatives if she broke off the affair.

“She repeatedly requested Ambar to return the photographs but he refused. Left with no other option, the woman lodged a complaint with Kasba police station,” the officer said.