A head constable posted at the Police Headquarters in Sector 9 was shot dead while asleep at his residence in Sector 22-A in the early hours of Friday, police said.The deceased has been identified as Nitin Kumar. His wife and son were present in the house at the time of the incident.According to police, a call was received at the Sector 22 police post around 8.50 am, following which a team rushed to the spot. A forensic team was called to collect evidence and a country-made pistol was recovered from the roof of the house.Kumar’s body was shifted to the mortuary of Government Multi-Speciality Hospital (GMSH), Sector 16.Police said the deceased’s son, Armaan, has been apprehended for questioning. Investigators suspect a family dispute may have led to the shooting.Son has criminal recordSources said Armaan has a criminal record. On the intervening night of February 24–25 this year, he allegedly rammed his Thar SUV into a motorcycle, killing two persons. He was reportedly out on bail in that case at the time of Friday’s incident.Police have registered a case and are investigating the motive behind the killing. Further details are awaited.