Rami Abdul-Rahman of the UK-based Syrian Observatory for Human Rights said he has received dozens of such videos and is growing increasingly concerned about the behavior of opposition fighters.
“Human rights are human rights. You cannot differentiate,” said Abdul-Rahman, who relies on a network of opposition activists to provide daily updates on fighting and casualties.
Both Abdul-Rahman and Peter Bouckaert of the international group Human Rights Watch said summary executions appear common.
“Rebel abuses pale in comparison to the level of executions and other atrocities committed by the regime, but it is an issue of serious concern,” Bouckaert said. “We do see quite regular cases of executions of captured soldiers and suspected regime supporters.”
Investigators acknowledge that videos can be manipulated and that witness accounts and other corroborating evidence are needed.
Al-Dada, the rebel army official, alleged that videos purportedly showing rebels killing captives had been doctored, and that some in fact showed regime soldiers executing defectors or dissidents.
Amnesty said it investigated one of the most shocking videos of recent months — what appears to show the beheading of two Syrian army officers abducted by rebels in August in the town of Deir al-Zour.
Nasser said researchers contacted the families of the two men, Colonel Fuad Abd al-Rahman and Colonel Izz al-Din Badr.
The relatives said the kidnappers, identifying themselves as members of an armed opposition group, contacted the families shortly after the abductions and demanded ransom. Negotiations ensued, but the kidnappers eventually informed the families that the two men had been killed, Amnesty said. Video of the purported killing first emerged in November.
Amnesty’s Nasser said she believes the video is authentic, noting that the families identified the slain men. She said a witness confirmed that the killing took place and provided a location.
Amnesty said there has been an increase in summary executions since the start of the conflict, but that it is impossible to estimate how many people have been killed this way.