Sandeep Dahiya, 35, was posted at Lahori Gate police station from December 21, 2017.
The Delhi Police has arrested its sub-inspector Sandeep Dahiya who allegedly shot at and injured his female friend here and later killed his father-in-law in Rohtak, officials said on Tuesday.
"Sandeep Dahiya has been arrested. He was picked up from Rohini. He is being interrogated and will be produced before the magistrate concerned," a senior police official said.
Mr Dahiya, 35, was posted at Lahori Gate police station from December 21, 2017.
According to the Delhi Police, Mr Dahiya had allegedly shot at his woman friend on Sunday during a quarrel with her in his car in north Delhi's Alipur area.
Another Delhi Police sub-inspector, Jaiveer, posted at Shahbad Dairy police station, had spotted the woman lying on the side of the road while he was crossing the Sai Mandir on the G T Karnal road and had taken her to a nearby hospital.
On the way, the woman had revealed that she has been shot by Dahiya, presently posted at Lahori Gate police station. The woman and Dahiya were having an affair since last year.
He was on the run after this incident and allegedly also shot dead his 60-year-old father-in-law outside his house in Haryana's Rohtak district on Monday morning.
The SI's wife told the Rohtak district police that they had been living separately for some time due to strained marital relations and also alleged that her husband had earlier threatened that he would kill her father.
The Rohtak Police on Monday had said the victim, identified as Ranbir, was cleaning a drain outside his house when he was shot.
A CCTV camera installed in the street showed an SUV with a Delhi registration number, leaving the area after the crime was committed.
Mr Ranbir was allegedly shot in the forehead and he died within minutes. His family members rushed outside the house and found him lying motionless.
Mr Dahiya had joined the Delhi Police in 2006 as a constable and became a sub-inspector in 2010 after clearing an examination. He was residing at Shalimar Bagh Police Colony.
He was on medical rest for two days and joined duty on Friday. Since he has been the division officer, 9MM pistol with 10 rounds was allotted to him.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)