Top-listed criminal Tariq Saif Mamun was killed over dominance in Dhaka's underworld, said Detective Branch (DB) chief Mohammad Shafiqul Islam.

The murder was executed on the instructions of Roni, an associate of "notorious gangster" Sanjidul Islam Emon, he said. "The two gunmen involved in the attack were each paid Tk 1 lakh."

Speaking at a press briefing at the DMP Media Centre today, Shafiqul said eight to nine members of the gang took positions near the court area to ensure the success of the attack.

Mamun was shot dead in broad daylight near the gate of Dhaka National Medical College Hospital on November 10, moments after he returned from appearing before a court.

"The DB police have so far arrested five suspects, including the two shooters, and recovered two firearms used in the murder," the DB chief said.

The arrestees are Faruk alias Foysal, Robin alias Piyash, Shamim, Rubel, and Yousuf. Among them, Faruk and Robin directly opened fire on Mamun, he added.

Shafiqul said the group had made several failed attempts to assassinate Mamun before finally succeeding on November 10.