They are also looking into an allegation raised by the sisters of deceased police official Akram Hossain to know whether his death was linked to the Mitu murder, Mohammed Kamruzzaman, additional deputy commissioner (ADC) of detective branch (north) of Chittagong Metropolitan Police, told the Dhaka Tribune.
The investigators are still quizzing Babul Akter, his two cousins, and Mitu’s father Mosharraf Hossain and mother Shaheda Mosharraf Nila.
On June 5 last year, Mitu was stabbed and shot dead by assailants at the GEC intersection in Chittagong city, when she was going to drop her son on a school bus.
Babul filed the murder case with the city’s Panchlaish police station the following day. Seven accused have so far been arrested.
However, prime accused Kamrul Islam Musa alias Musa Sikdar is yet to be arrested, but his wife Panna Akter claimed that her husband was arrested on June 22.
The police have already announced a Tk5 lakh reward for assistance in arresting Musa, who had been working for Babul as an informant.
“We are on the move to arrest Musa who plotted the murder,” said Kamruzzaman, also the investigation officer (IO) of the case.
Contacted, Panna Akhter claimed: “My husband was picked up by detectives. I did not file any complaint as police repeatedly threatened me with dire consequences.”
Last month, the sisters of Sub-inspector Akram -- who was killed in a reported motorbike accident on December 24, 2015 -- accused Babul of murdering their brother as he (Babul) had an extra-marital affair with Akram’s wife Bonni.
They raised the same allegation at a press conference on February 3 and said Babul hired goons to kill Akram.
On January 26, Mitu’s father Mosharraf urged the IO to probe into Babul’s alleged extra-marital relationship with Bonni after Akram’s sisters had raised the allegation.