A 25-year-old Delhi Police constable and his 55-year-old father were shot dead in Haryana’s Sonipat on Saturday, allegedly by a relative over a dispute related to irrigation of fields, the police said. “Parvinder and his father Ishwar were gunned down in Gorad,” said SHO (Kharkhoda police station) Pradeep Singh. The accused, who have been booked, are yet to be arrested.