Rapid Action Battalion (RAB) has apprehended the prime accused of double murder from the city's Akbarshah area.
The arrest was made in the early hours of Thursday.
The arrestee was identified as Md Faruk, 33.
Soon after the murders were committed, the elite force launched a shadow investigation.
At one stage of the investigation, RAB-7 came to know about the whereabouts of the prime accused.
Later, a team of RAB-7 conducted a drive at the city’s Pakkar Matha area under Akbarshah police station and nabbed the prime accused.
After a search of the arrestee, a foreign-made pistol, two rounds of bullets and a knife were recovered.
During primary interrogation, the arrestee confessed to his involvement with the murder.
He said, at one stage of an altercation, Faruk killed Gulnahar Begum, and her son as he witnessed the murder.
The arrestee was handed over to Chandgaon police station for further legal procedures.
Previously on August 24, a 33-year old woman and her nine-year-old son were murdered at Pathania Goda area under the city’s Chandgaon police station.
After returning home from the workplace, Moyuri Aktar saw that her mother and younger brother were lying in a pool of blood.
Later, she lodged murder a case with Chandgaon police station accusing Faruk.