
The arrestees were identified as Jiasmin alias Jesmin, 37, Sajib Alam, 29, Ripon Mia, 42, and Faruk Khan, 50.
Police said five robbers entered a flat on the fifth floor of a 10-storey building near Roxy Lane in Mahdinagar around 7:30pm on July 18 on the pretext of inspecting it for rent.
They later tied up the residents of the flat and looted Tk 20 lakh in cash, three tolas of gold ornaments and four mobile phone sets before fleeing the scene.
After receiving information, police visited the spot and launched an investigation. During the investigation and analysis of CCTV footage, police identified the suspected robbers.
Later, a team of police conducted a drive in Muslimbagh area of Kamrangirchar around 12:10am on Wednesday and arrested Sajib, said DMP Additional Deputy Commissioner (ADC) Niaz Mehedi.
Following interrogation, police arrested Ripon from the same area and recovered Tk 1 lakh from his possession.
Later, the same team conducted a drive in the Chand Mosque area and arrested Faruk with Tk 1 lakh and gold ornaments.
Police later found that Jesmin, a resident of the seventh floor of the same building where the robbery took place, was the mastermind behind the incident.
She was subsequently arrested from the building and Tk 20,000 was recovered from her possession.
According to the police, Jesmin was a regular visitor to the victims' flat and was aware that a large amount of cash was kept there.
She allegedly planned the robbery with some people she knew and received the robbers on the ground floor on the day of the incident and ensured their safe exit, reports UNB.
Eight people were involved in the robbery, said police.
Efforts are underway to arrest the remaining suspects, said Niaz Mehedi.