The witness of killings in Muzaffarnagar riots was shot dead on Monday at Khatoli.
The communal clashes in Muzaffarnagar and its adjoining areas in August and September 2013 had claimed more than 60 lives while over 40,000 people were displaced.
Ashfaq, a witness in the case, was shot dead in Muzaffarnagar's Khatoli, Circle Officer Ashish Kumar said.
Eight people are facing trial for allegedly killing Ashfaq's brothers and the next hearing was scheduled for March 25.
Police are examining CCTV footage to identify the shooter, Kumar said, adding that Ashfaq was killed when he was going to deliver milk.
He had witnessed the killing of his two brothers -- Nawab and Shahid -- during the riots and earlier, had also been threatened with dire consequences if he did not withdraw his case, police said.
Reportedly, Ashfaq had also sought police protection following the threats.