The Rapid Action Battalion (RAB) has arrested the prime suspect from Gopalganj over recent murders of a woman and her 18-year-old son in Dhaka.
RAB-3 chief Lt Col Md Emranul Hasan said they arrested prime suspect Al Amin Jony early on Saturday from Gopalganj's Maksudpur area.
"He has confessed to the murders and revealing further information," said the RAB officer.
According to bdnews24.com, a media briefing will be held later to provide detail information, he said.
Shamsun Nahar and her son Sajjadul Karim Shaon were found murdered on Wednesday in their at the capital's Kakrail.
Following the murders, police detained Shamsun Nahar's husband businessman Abdul Karim.
The next day police arrested a woman, Sharmin Aktar Mukta, and said she is the third wife of Karim, whose business concerns range from grocery to producing films.
Prime suspect Al Amin is Mukta's brother.
The murder case started by Shamsun Nahar's brother Ashraf Ali accuses Karim, Mukta, Al Amin and several other unidentified people.
According to the case details, Mukta had come to Shamsun Nahar a few months ago and threatened her.
Quoting witnesses, plaintiff Ahsraf Ali claimed that Al Amin Jony along with few others murdered the mother and son.
Forty-six-year-old Shamsun Nahar is the first wife of Karim. The couple had three sons, including Shaon who was murdered the same day. The other two sons live abroad.
Police said Karim married her 28 years ago. Later, he married a woman named Farida, but the marriage did not last. Four years ago, Karim married Mukta.