"We got a hard copy of the photos of two persons from the video footage of the marriage ceremony, who were not identified either by groom or bride sides," Additional Director General of Police (Law and Order) Daljeet Singh Chaudhary told PTI.
The hard copy somehow got leaked to the media, but both the persons were not suspects, he said, adding one person has turned up and another will also come forward soon.
Uttar Pradesh Police chief Javeed Ahmed has formed several probe teams who are pursuing some leads that have emerged from the scene of crime.
Chaudhary said an empty shell has been recovered from the spot where Ahmed was killed.
"We will be able to say anything concrete after a day or two," he said.
Several agencies, including Delhi Police, are probing the gunning down of the NIA officer and looking into suspected movement of two bikers.
NIA has also been providing all assistance to the UP police including scanning of the CCTV footage to make the picture of the suspects clearer, sources said.
Asked about two bike-borne men visible in a CCTV footage, Jain said these "aspects" were being looked into.
"Monitoring of the case is being done at high-level, but we are not in a position to share any information. When we have something concrete we will share," he said.
Uttar Pradesh Chief Minister Akhilesh Yadav, while expressing profound grief over the death of Ahmed, had announced an ex-gratia of Rs 20 lakh to his family.
He assured Ahmed's family that adequate security would be provided to them.
Ahmed, an assistant commandant with BSF who was on deputation in NIA, was returning to Sahaspur from the wedding of his niece when two unidentified bike-borne assailants stopped his car and shot at him.
His wife was also injured in the incident while his two children, on the back seat of the car being driven by the deceased, were safe. Ahmed's wife was admitted to Fortis hospital in Noida and was under observation.