Mufti Harun Izhar, education and cultural affairs secretary of the now-dissolved central committee of Hefazat-e-Islam, has been arrested over the violence during the Indian prime minister's visit last month.
Rab officials picked him up from Jamiyatul Ulum Al Islamia Madrasa, known as Lalkhan Bazar madrasa, in Chattogram early yesterday.
RAB-7 Commanding Officer Lieutenant Colonel Moshiour Rahman Jewel told The Daily Star, "We detained Harun Izhar after his involvement was found in the violence in Hathazari on March 26 during the visit of Indian Prime Minister Narendra Modi.
"He will be handed over to Hathazari Police Station with which eight cases were lodged over the Hefazat mayhem."
Once an active organiser of banned militant outfit Harkat-ul-Jihad-al-Islami (Huji), Harun was arrested at least two times before this for being involved in the 2013 bomb blast in the Lalkhan Bazar madrasa and conspiring with Lashkar-e-Taiba to launch an attack on the US Embassy in Dhaka in 2009.
Senior police officials of Chattogram Metropolitan Police said after the fierce clash in Hathazari which left four people dead, Harun appeared at the Chattogram Medical College Hospital with his followers on the evening of March 26.
Under pressure from him, the authorities handed over the bodies of the deceasedto family members without autopsies the next day.
His followers also confined Hefazat chief Junayed Babunagri to the hospital morgue for about more than three hours to make him announce tough anti-government programmes if the bodies were kept for autopsy.
The rift between the top leaders of Hefazat and Harun was reflected in the public speech he gave in front of the CMCH morgue on March 27.
He said, "The responsibility for the killing in Hathazari lies with the Hefazat's top leaders. We have seen your [top Hefazat leaders'] abilities in this regard. You have no power to take away the bodies from the state. I stayed here for the last 24 hours but no central leaders phoned me or asked me about the updates."
Addressing the top Hefazat leaders, he further said, "You should know that I never care about your words. We will form an alternative force with the help of young faces of the organisation."
Harun's father Mufti Izharul Islam Chowdhury, founder of the Lalkhan Bazar madrasa and former nayeb-e-ameer of Hefazat, played a significant role in spreading the Huji network across the country since the early '90s.
Earlier, the madrasa used to be the training centre of Huji members and it has been under scanner since the bomb blast in 2013, counterterrorism investigators said.
Seeking anonymity, a former top official of CMP, who investigated several terror incidents of Lalkhan Bazar, told the Daily Star, "After coming out from jail on bail, Harun started to present himself as an Islamic scholar and enhanced his connection with a section of Hefazat leaders."
"After the bomb blast," he added, "we put the madrasa under watch and several times raided it during unrests involving Hefazat-e-Islam."
Officials say Harun has been working to form an "updated version of Huji" hiding behind the Qawmi madrasa-based Hefazat-e-Islam and to reorganise radical activists in his Lalkhan Bazar madrasa.
Contacted, Additional Deputy Commissioner (ADC-Operation) of CMP's Counter Terrorism Unit Asif Mohiuddin said, "This madrasa is under our surveillance. We have collecting some data and gathered information."
Officials say Harun was detained with two others from his madrasa in November 2009 for their plot to attack the US Embassy with the help of Pakistan-based terror group Lashkar-e-Taiba. He later came out on bail.
Detectives at the time traced cash flow from abroad to finance the attacks in Bangladesh.
The names of Harun and his father once again hogged the headlines after the blast at the madrasa hostel on October 7, 2013. Three including a bomb expert were killed in the blast, said the investigators.
After the incident, police filed three cases with Khulshi Police Station. Harun was detained on October 10, 2013 and his father on August 7, 2015, and both later got bail.
Police submitted the charge sheet on February 10, 2014, naming nine persons including the father and son.
The whereabouts of Mufti Izharul Islam are not known.
As the court is closed due to the ongoing pandemic, The Daily Star correspondent could not get the updates of the trials in the cases. Court sources said the cases were sent to the Speedy Trial Tribunal in Chattogram.