Mohammad Rameez and Nazir Ahmad were detained for questioning yesterday after police investigation suggested that the duo had a role in the death of Dar in army firing on July 24, they said.
Police said Rameez, a former militant, was working as an informer for the Army.
Meanwhile, Kashmir IGP S M Sahai said the investigation into the case was on and sharing the details at this moment can hamper the progress.
"We will share the details of the investigation once we reach the conclusion," he said.
Dar, a resident of Aloosa village, was killed allegedly in army firing last week in Bandipora, triggering protests by locals who claimed that he was an innocent local youth and not a militant.
While army is maintaining that Dar was killed following an exchange of firing with militants, the family of the deceased claim he was taken into custody and later shot dead in cold blood.
Defence Minister A K Antony and the state government have ordered separate probes into the incident.