The Taliban fighters who killed Amrullah Saleh's brother in Panjhsir on Thursday did not allow Amrullah Saleh's family members to bury the body, a family member told Reuters.
The news that Saleh's brother Rohullah Azizi was killed came days after Taliban forces took control of the provincial centre of Panjshir, the last province holding out against them.
"They killed him yesterday and would not let us bury him. They kept saying his body should rot," news agency Reuters quoted Ebadullah as saying.
He was identified by the Taliban in Panjshir Valley during clashes on Thursday night, reports said, adding that he was tortured and executed by Taliban fighters.
The whereabouts of Amrullah Saleh and Ahmad Massoud are not yet known. A photo of a Taliban fighter posing with guns in front of books has been floated on social media, claiming that this is the same place from where Amrullah Saleh recently issued a video statement claiming that he was still in Panjshir.
The National Resistance Front of Afghanistan, which groups opposition forces loyal to local leader Ahmad Massoud, has pledged to continue opposing the Taliban even after the fall of Panjshir's provincial capital Bazarak.