A 34-year-old man was arrested in connection with the shootout under the Dwarka Mod metro station last week, police officials said on Monday.
The accused has been identified as Gopal Kishan alias Pali, a resident of Najafgarh, and active member of 'Pradeep Solanki' gang.
Earlier, 20-year-old Ankit Dabas was arrested in connection with the encounter, police said.
After Solanki's arrest, Kishan headed the extorting racket for the gang, police said.
On May 19, two suspected criminals were killed in the shootout, an outcome of a property dispute, between rival gangs near the Dwarka Mor metro station in South West Delhi, police said.
Kishan was providing live tracking information to criminals Vikas Dalal and his associates. He trailed deceased Praveen Gehlot on motorcycle with backup plan to shoot him if others missed the target.
However, Dalal was also shot dead by PCR van staff, a senior police officer said.
The arrest was made after police got a tip-off on May 25 that a criminal who was the main conspirator would come near Sai Baba Mandir on Najafgarh Uttam Nagar Road to meet someone, said Anto Alphonse, Deputy Commissioner of Police (Dwarka) said.
One country made pistol with two cartridges was seized from the possession of the accused, he said.
During interrogation, the accused confessed that he was the key man working on the directions of Pradeep Solanki, for eliminating Praveen Gahlot.
He further revealed that following a land dispute between Pradeep Solanki and Praveen Gehlot, Solanki directed his associates to eliminate Gehlot and absconding gangster Vikas Dalal took the command to complete the task.
"Solanki also directed Kishan to act as back up shooter and also provide live tracking information to Dalal regarding their target (Gehlot)," the DCP said.
Kishan carried out several recces of the areas in Uttam Nagar to note movements of Golu and provided input to Dalal. The gang prepared a plan and decided that it shall be executed on May 19, the DCP said.
As per plan, Kishan reached near Nawada Metro Station on a motorcycle to track the movements of Golu while Vikas Dalal, along with his two aids- Ankit Dabas and Cheeta waited in a swift car for the exact information from Kishan, the DCP added.
When Gehlot was spotted in his Ritz car going towards Dwarka Mod Metro Station. Kishan passed this information to Vikas Dalal, who immediately started trailing the Ritz car.
Kishan, in possession of a loaded pistol, also followed them with a back-up plan to shoot Gehlot, if something went wrong, the officer said.
Vikas was shot dead by a PCR constable, while his associates Ankit Dabas, Cheeta and Kishan fled from the spot, the police said adding that further investigation is going on.