Police claimed to have arrested the 'mastermind' of the killing of Superintendent of Police Babul Akter's wife Mahmuda Khanam Mitu.
The arrested person is identified as Shahzaman alias Robin, 28, son of Mohammad Shahjahan of Laksham in Comilla.
Robin was detained from Shital Jhorna area under Bayezid Police Station in the port city, said Chittagong Metropolitan Police (CMP) Commissioner Iqbal Bahar at a press briefing on Saturday afternoon.
Police suspect that the arrested man is the same person who was seen walking to the killing spot from near a lamppost of the place where the CCTV was installed.
The CMP commissioner said the man was seen talking over a mobile phone while following Mitu.
He might have been communicating with his accomplices over mobile phone before killing, the CMP commissioner said.
Earlier on June 5, three assailants reportedly stabbed and shot dead Mitu, 32, at GEC intersection in the port city around 6:45am.