"The magistrate ordered them to be quizzed in custody for eight days as police produced them in a court," an official at suburban Narayanganj court told reporters.
However, there was no comment from police on the arrests of the five junior RAB personnel and their alleged role in the gruesome murder after three were arrested soon after the incident.
The three -- an army lieutenant colonel, a major and a navy lieutenant commander - earlier confessed to their involvement before a magistrate after weeks of questioning in police custody after authorities sacked them from service.
The assailants kidnapped seven people including a city councillor and a lawyer from the suburban river port city on April 27 and their nearly decomposed bodies were recovered from the Shitalakya River.
Slain councillor Nazrul Islam's relatives earlier had alleged that his fellow councillor Nur Hossain had bribed the RAB officials to eliminate him in exchange of Taka 6 crore (over USD 76000).
Sarkar was apparently trying to follow the abductors in his own car. Several witnesses including ordinary passersby later testified before a high level investigation committee as well as media that they saw the victims were being dragged into RAB cars while they were being kidnapped.
Immediately after the incident Hossain fled the country to take refuge in India but the West Bengal police tracked him down while he is now in a jail there on charges of intrusion while Bangladesh asked New Delhi for his return to face justice.
Hossain is likely to be the first Bangladeshi to be deported from India since the signing of the extradition act between the two countries in December 2013.
