They detained Masum in Dhaka on Sunday night, Md Moyeen Uddin, an additional superintendent of Police Bureau of Investigation in the port city, told bdnews24.com.
He was also criticised when he was pictured in the media brandishing a gun during a clash.
Recently, the authorities cancelled his gun licence when he submitted his two registered firearms to a police station following a complaint filed by councillor of the ward F Kabir Manik, who cited security concerns.
A group of assailants beat to death Sudipta, a former student of Chittagong Government City College and an assistant secretary of BCL's port city unit, at Lalkhan Bazar on Oct 6 in 2017.
Sudipta's friends have blamed the followers of Masum for the murder. They said Sudipta was killed for 'criticising the rival faction for the bad state of Chattogram BCL on social media'.
Masum himself had been a BCL leader. He worked as president of the organisation’s Chittagong City College unit in 1997-98.
He was abroad from a long time after spending time in jail during the BNP-Jamaat-e-Islami government.
His rival faction in the ruling party alleges his involvement with at least two other murders.
Known as a follower of late mayor ABM Mohiuddin Chowdhury, Masum is now a supporter of incumbent Mayor AJM Nasir Uddin.
Masum had also identified himself as a follower of former minister Afsarul Ameen MP several times.