The Union Minister accompanied by UPCC president Nirmal Khatri visited the Haq's house and met his mother, father and wife.
Later, talking to media, Singh without naming anyone said action will be taken against those found guilty in the probe.
"We should have faith in the CBI probe," Singh said.
Meanwhile, Anjuman Islamia president Munna Lari said special prayers were offered after Friday prayers for the slain police officer.
Haq, circle officer in Kunda from where Raja Bhaiya is a five-time MLA, was allegedly killed by a mob in Pratapgarh on Saturday when he had rushed there after a village head was shot dead over a land dispute.
The slain officer's wife has alleged that Raja Bhaiya, who resigned from the state Cabinet after an FIR was filed against him, had a hand in the attack.
Deoria: Union Minister of State for Home RPN Singh on Friday met the family of the slain UP DSP Zia-ul Haq at his native village here and assured that the CBI probing the case would expose the guilty.
First Published: Friday, March 08, 2013, 19:23