Assistant Superintendent of Police (ASP) Mizanur Rahman Talukder of Savar circle highway, who was found dead in the capital's Rupnagar a month ago, was killed by some muggers when he revealed his identity, said police.
On June 21, Mizanur was waiting outside his Uttara residence for a transport to reach his workplace when the muggers masquerading as driver and passengers arrived in a private car and picked him up.
When Mizanur revealed his identity, it scared the muggers.
They killed him not for his belongings but out of fear of getting into trouble, said Monirul Islam, chief of Counter-terrorism and Transnational Unit at Dhaka Metropolitan Police media centre yesterday.
Detectives arrested Shah Alam alias Alam alias Budda, 62, in Tongi on Saturday.
Alam's other accomplices are Mintu, Kamal alias Faruque and the driver, Jakir.
Alam admitted that he had hit Mizanur in the head with a heavy object and then others strangled him.
The killers dumped the body near Birualia Bridge, Monirul Islam added.