"If Nur Hossain has been arrested indeed, he will be brought to book," said Asaduzzaman Khan Kalam, State Minister for Home.
He expressed hope that Hossain's repatriation would be an easy process as the two countries inked an extradition treaty to exchange wanted criminals hiding in each other's soil.
Hossain, a local leader of ruling Awami League, is the alleged key-mastermind of the murders of seven people in suburban Narayanganj two months ago.
The incident had sparked a massive public outcry as the families of the victims alleged that several personnel of elite anti-crime Rapid Action Battalion (RAB) were involved in the murders.
The seven persons including a city councillor and a lawyer were kidnapped by assailants from the suburban river port city on April 27 and their nearly decomposed bodies were retrieved from the Shitalakya River on May 1.
The incident embarrassed the Sheikh Hasina's government and prompted it to immediately sack two army and navy officers after the victims' families complained that Hossain, himself a city councillor, abducted and killed them in exchange of huge bribes.
The officers, however, were arrested subsequently under a High Court order as investigations were underway confining them at their cantonment residences confessing to their crime.
Several witnesses including ordinary passersby later testified before a high level investigation committee that they saw the victims were being dragged into cars.
Bangladesh sought Interpol's help to track down Hossain.
They also informed India to check on reports that he had fled to West Bengal after crossing the porous border.
Hossain along with two other Bangladeshi nationals was arrested in Kolkata last night for entering India without valid documents.
Bangladesh police has so far arrested 16 suspects while Hossain was on the run.