Sources at police said they have quizzed most of the relevant witnesses regarding the death of Mosarat Jahan Munia, but they are yet to interrogate Bashundhara Group Managing Director Sayem Sobhan Anvir, the lone accused in the case of abetting suicide.
Gulshan police said official documents showed that Sayem is still in Bangladesh, although his wife, younger brother and some other family members have left the country for Dubai one day after Mosarat's death.
Police, however, did not reveal anything about Sayem's current location.
Cops, along with Mosarat's family members, recovered her body hanging from the ceiling fan in her flat on 26 April.
The apartment's owner Ibrahim Ripon was present when police broke the flat's door and recovered the body.
On Wednesday, Ripon said police quizzed him, his wife and the building's security guard and recorded their statements around four to five days ago.
Ripon also said he rented the apartment to Mosarat, where she lived since 1 March this year, in presence of her sister Nusrat Jahan.
The building's security guard Ayub Ali said Sayem used to visit the apartment often.
Police said Mosarat had been in a relationship with Sayem for two years.
Our correspondent could not reach Deputy Commissioner of Police (Gulshan Division) Sudip Kumar Chakraborty by phone on Wednesday. He also did not reply to texts for comment regarding the matter.
Earlier, Sudip said they were prioritising the collection of evidences and analysing them to establish whether someone abetted Mosarat's suicide.
Meanwhile, Muktijoddha Sangsad Santan Command in Cumilla town organised a human chain demanding justice for Mosarat on Wednesday.
The college girl's sister Nusrat, Awami League lawmaker AKM Bahauddin Bahar, and other local ruling party leaders attended the human chain.
Speakers at the event alleged that Mosarat was murdered in planned way. However, Nusrat has filed a case against Sayem Sobhan Anvir alleging that he abetted Mosarat's suicide.
At the human chain, Nusrat said Sayem lured Mosarat with a false promise of marriage and deceived her.
Awami League lawmaker AKM Bahauddin Bahar warned of a tougher movement if justice is not carried out for Mosarat's murder.
A Dhaka court on 27 April imposed a travel ban on Sayem in response to the Gulshan police's appeal.
The police also seized six dairies of Mosarat from her flat.