The authorities investigating the death of Munia, who apparently committed suicide in her Gulshan apartment, said her hand-written diaries are now the key evidence in solving the case.
"We have got vital evidence from reading all of her six diaries. These would be a crucial component in the investigation," said Sudip Kumar Chakraborty, deputy commissioner of Dhaka Metropolitan Police's Gulshan Division.
He also said, "Currently, we are focusing on two points – abetting suicide and the intention behind abetting."
Mosarat Jahan Munia, 21, second-year college student, was found dead in her flat in the capital's Gulshan-2 area on Monday night.
Following her death, Munia's elder sister Nusrat Jahan filed a case under Section 306 of the Penal Code with the Gulshan police station accusing Bashundhara Group Managing Director Sayem Sobhan Anvir of "abetment of suicide."
Afterwards, a Dhaka court imposed a travel ban on Anvir, barring him from leaving the country.
"Hopefully we will come to a positive conclusion after getting the forensic and post-mortem reports. Now we are collecting and analysing all the evidence," said the deputy commissioner of police.
Police have collected several "digital footprints" including mobile phones, and CCTV footage in order to get an insight into the sequences of the event that led to Munia's death.
Sudip Kumar Chakraborty also said it is important to know the cause of the victim's death.
"Police have contacted autopsy experts. Apart from that, the police have requested the concerned authorities for supplying the DNA profile and other things that are needed in this regard. Evidence suggests that the police can bring the case to a critical stage by gathering material evidence. The next legal actions will be taken based on those evidences," he added.
Asked if there was any obligation to collect evidence before arresting the accused in a case of abetting suicide, the deputy commissioner of police said there was no obstacle to apprehending the accused in any case as per the criminal procedure and penal code, but it is vital to establish that someone abetted the victim to commit suicide and that person's intention behind it.
"Since the case is widely discussed and sensational, all of us are working together to bring justice to the victims and we will all work to establish the rule of law," Sudip Kumar Chakraborty added.
Police did not find proof of any suspicious person's presence in Munia's flat in the last two days before her death. Anvir did not go to the house on the day of her death or the day before that. However, he went to the house for two days in a row before that and the police have footage of it, said sources in police.
Sudip Kumar Chakraborty said, "According to the primary investigation, the inquest report and autopsy, Munia had committed suicide. Her limbs were blue and slightly swollen from hanging. There were no signs of injuries or bruises anywhere else on the body"
Meanwhile, Sharun Chowdhury, son of Awami League's Whip Shamsul Haque Chowdhury, has termed the screenshot of an alleged conversation between him and Munia fabricated.
When contacted in this regard, Sharun Chowdhury said, "The posts circulating in social media claiming to be a conversation between Bashundhara Group managing director's girlfriend and me are fake and fabricated."
He also said, "No one claiming to be members of the law enforcement agencies spoke to me. However, a person using a phone number from London asked me about the authenticity of the screenshot. I told him these were not true. He was not a member of the law enforcement forces. If any of the law enforcers of our country called, they would call me from a Bangladeshi number or introduce themselves as such."
Nazmul Hasan, additional deputy commissioner of Gulshan Division also told TBS that they had not interrogated anyone named Sharun Chowdhury regarding the death of Munia.
Meanwhile, Anvir has filed a petition with the High Court seeking anticipatory bail in the case filed over Munia's death.
The bench of Justice Mamnoon Rahman and Justice Khandaker Diliruzzaman is scheduled to hear the petition on Thursday.
Home Minister Asaduzzaman Khan Kamal yesterday said actions will be taken as per law if anyone found involved in the suicide of the college girl.
"Investigation is underway in the case filed over her suicide," said the minister on Wednesday.