The incident took place last week and the constable identified as Varun Tomar (27), posted with third battalion of Delhi Armed Police, was arrested yesterday.
According to a senior police officer, the incident took place on March 14, when Tomar along with his associates Ashish and Sandeep went to the Ravi's house behind Yusuf Sarai market area and allegedly pulled the trigger twice threatening to shoot him over a dispute the latter had with his associates.
Further probe is on, the officer added.