The victim, identified as Praveen, sustained two bullet injuries and is recovering at a private hospital in south Delhi, a senior police official said.
The prime suspect in the case happens to be a person whose relative was allegedly murdered by Praveen around four years ago, the official said.
Praveen and his cousin had undergone trial for the murder of a man in Gurgaon. While Praveen was acquitted in the case, his cousin is serving his sentence at a jail in Haryana.
A case of attempt to murder has been registered and the police are searching the potential whereabouts of the accused persons, the official added.