Locals said after visiting his mother's grave in Mahishbathan village of the upazila, Razzak was sitting at a tea stall around midnight when a group of miscreants led by his nephew Omar Khayyam Sarkar Ropon surrounded him with 10-12 motorcycles and stabbed him indiscriminately with a sharp weapon.
He then tried to escape while opening fire on the miscreants using his licensed pistol, but Razzak fell injured on the road in Trimohoni.
The police rescued him and took him to Bogura Shahid Ziaur Rahman Medical College and Hospital where the physician declared him dead.
Bogura Sadar police inspector (investigation) Zahidul Haque said Omar Khayyam, nephew of the slain Razzak, was arrested on Wednesday morning.
Besides, Ropon's associates Abdul Hannan, Johnny and Al Amin were admitted to Bougra Shaheed Ziaur Rahman Medical College Hospital with bullet wounds and were also detained, he added.
One foreign pistol and several bullet casings were recovered from the spot.
No case has been filed on behalf of the victim's family so far. The body is in the hospital morgue and will be handed over to the family after autopsy, said the inspector.