"We have filed an application to recall Avik Sengupta as we need some clarification regarding evidence submitted by the Investigating Officer in the case," said defence lawyer Abdul Wahab Khan.
Sengupta, also a lawyer and Purkayastha's fiancee, was the key witness in the case. The 28-year-old died on November 15 last year due to a brain disorder.
Khan said the defence needs certain clarifications from Sengupta about a key piece of evidence submitted by the Investigating Officer.
The application will come for hearing in due course of time.
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Purkayastha was allegedly murdered by a security guard, Sajjad Mughal, employed at her building in Wadala area on August 9, 2012.
Mughal (22), a native of Jammu and Kashmir, killed the 25-year-old, daughter of IAS officer Atanu Purkayastha, for 'resisting his advances', police have said.
Mughal was later arrested.