A local Awami League leader had allegedly plotted the murder of Jahidul Islam Tipu in Dhaka's Shahjahanpur, according to the Rapid Action Battalion, reports bdnews24.com.
The elite police unit identified Omar Farooq, general secretary of the ruling party's Dhaka South Ward-10 unit, as the mastermind behind the shooting which also resulted in the death of bystander Samia Afnan Jamal Prity on Mar 24.
Farooq was aiming to assert his dominance by taking out Tipu, RAB spokesman Khandaker Al-Moin said at a media briefing on Saturday.
He was arrested along with three other suspects -- Nasir Uddin, Abu Saleh Sikder and Morshedul Alam on Friday.
Earlier, Dhaka Metro-politan Police's Detective Branch (DB) arrested Masum Mohammad Akash and Arfan Ullah Damal in connection with the case. They have since been placed on remand.
According to the DB, it was Akash who had shot Tipu.
Tipu, a former general secretary of the party's Motijheel unit in Dhaka, was gunned down under a flyover outside Manama Bhaban in the Amtala area.
A gunman wearing a helmet on a motorcycle pulled up next to Tipu's microbus and opened fire.
Prity, a student of Begum Badrunnesa Government Girls' College, was also killed by a stray bullet, while Tipu's chauffeur 'Munna' was injured.
Within moments of pulling the trigger, the assailant jumped over a divider, hopped on a motorcycle waiting on the other side of the road and fled.
Tipu's wife Farzana Islam Dolly, a local councillor of the city corporation, subsequently filed a case against unidentified suspects with the Shahjahanpur Police Station on March 25.
She alleged that Tipu had received a death threat over the phone some days ago.
UNB report adds: An Awami League politician was among four people detained by the elite Rapid Action Battalion (Rab) in connection with the Shahjahanpur shooting in which ruling party member Zahidul Islam Tipu and a college student were killed.