With the arrest of Hasrat, the number of people taken into custody in this case has risen to seven, police said.
Yakub, an alleged cattle thief, died on the spot, while his other accomplices -- Sanwar (25), Khalid (22), Anwar (20) and Ankur (22) -- were injured in the shootout between the gang and police on January 18.
While the trio were later arrested, Hasrat and two others had managed to escape from the spot after the incident.
Police arrested Hasrat from near Seelampur Metro station yesterday and seized a loaded improvised pistol from him. The remaining two members were also arrested
"Hasrat has been remanded to two-day police custody and efforts are continuing to arrest another accused Asif," a senior police official said.
He said the 21-year-old youth is a casual labourer and does not have any source of regular income who fell into bad company at an early age.