"The entire Congress is with them in this hour of great tragedy and loss and they will get full justice," the Congress leader told reporters at the burial ground where he paid tribute to the slain police officer after meeting his family at their home in Jaffuar tola in Deoria.
Rahul, who was with the family for over an hour, is believed to have been apprised of the events leading to the murderous attack in Kunda in Pratapgarh district last week and the family's struggle for justice.
The Congress leader drove to Deoria from Gorakhpur to meet the family and offer his condolences.
Zia's family members refused to divulge details of the meeting with the Congress leader.
The sister-in-law of the slain officer said his widow Parveen Azad was unwell and not in a position to speak.
Raghuraj Pratap Singh alias Raja Bhaiya, a controversial UP politician was on Thursday booked by CBI under murder charges in the killing of Zia in Kunda in Pratapgarh last Saturday after the probe into the case was handed over to the central investigating agency.
Raja Bhaiya, a five-time Independent MLA from Kunda, was named in one of the four FIRs filed by CBI on the basis of complaint given by Parveen Azad in which his name figured. He also faced charges of criminal conspiracy.