Joint Commissioner of Police (Crime Branch) Ravindra Yadav said 26-year-old Deepak Tomar was arrested by Crime Branch from near Mongolpuri railway station on October 13.
He said Tomar committed his first murder in Rohtak for which he was convicted in 2008.
He was lodged in Gurgaon's Bhondsi jail from where he managed to get 21-day parole in July 2014 but didn't return, Yadav said.
They fired 21 rounds with country-made pistols to kill Jitender and Anil of Ranbir gang in his native village Ramala, the JCP said, adding a cash reward of Rs 5,000 announced on his arrest.
Again in September 2015, he and his accomplices allegedly killed Sohanveer in Baba Haridas Nagar area of Delhi.
The murder was a revenge killing because Sohanveer had allegedly thrashed Deepak in Rohtak jail, the JCP said.
He was also involved in robbing of a SUV from Nihal Vihar in Delhi in May 2015.
G Ram Gopal Naik, who led the Crime Branch team which arrested Tomar, said he committed "most of the murders" while he was out on bail or on parole.
"We have requested the court to not grant Deepak (Tomar) bail or parole since he has hatched most of the plans when he has got bail," he said.
During interrogation, he revealed that he was planning to commit 18 more murders and had a list of of people with whom he has had an enmity at his village, Naik added.
"He is a person who doesn't spare people who cross paths with him," he said.
A country-made weapon and three live cartridges have been recovered from him.
He was living at Shiv Ram Park area in Nangloi while on the run.
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