Jafar Qureshi was shot eight times outside his shop last evening. He was rushed to a nearby hospital but could not be saved, the police said.
The police said that 26 cases were registered against him at the Gandhi Nagar police station till 2008, including those of extorting money from local vendors and snatching.
Investigators said that they are probing all angles, including that of personal enmity or a monetary dispute.
"However, we are scanning his call details and even his going through his financial dealings to ascertain whether those could have led to his killing," said a senior police officer.
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Police are also going through his criminal record and seeing whether any of his rivals could have carried out the killing.
Qureshi is survived by his wife and three children, the youngest being seven years old.
His killing comes close on the heels of two other similar incidents in which on Sunday, one Wazid was shot dead in Brahmpuri and 22-year-old Aarif Khan was killed in an area near Brahmpuri