IS killed the 19-year-old male student on Thursday after kidnapping more than 30 people, mostly women and children, from a village in Sweida during a deadly rampage last week, the head of the Sweida24 news website Nour Radwan told AFP.
Quoting relatives, Radwan, who was speaking from Sweida, said the young man was taken from the village of Al-Shabki on July 25 along with his mother.
His family received two videos, the first showing him being decapitated and the second of him speaking before being killed as well as images of his body after his death, Radwan said.
Sweida24 posted online part of a second video, which was seen by AFP, showing a young man who appeared to be sitting on the ground in a rocky landscape.
He is wearing a black T-shirt and tracksuit bottoms, and his hands are tied behind his back.
The video could not be independently verified.
IS has not claimed the kidnappings and did not publish the video on their usual channels.
The Syrian Observatory for Human Rights, a Britain-based war monitor, said the young man's execution was the first since the kidnappings.
The execution came "after the failure of talks between IS and regime forces over the transfer of IS fighters from the southwest of Daraa province to the Badiya" desert, said the Observatory.
It also follows the execution of 50 IS fighters and civilians in Daraa province earlier this week at the hands of rebels, the monitor said.
On Friday, a top Druze religious leader said Syrian regime ally Russia was in talks with the jihadists over the release of those abducted in Sweida.
IS jihadists have lost much of the territory they once controlled in Syria after overruning large swathes of it in 2014, but they retain a presence in the east of the country and in the vast Badiya desert that sweeps through its south.
'Failure of talks'
IS fighters once held a southwestern patch of the neighbouring province of Daraa, but regime forces have in recent weeks ousted them from all of the towns and villages there.
Syria's state media have said regime troops are pursuing the last remaining jihadists who fled to nearby valleys.
In areas it has retaken from rebels and jihadists in recent years, the Russia-backed regime has sometimes negotiated to take back control of land in exchange for the transfer of fighters to other parts of Syria.
On July 25, IS carried out a series of attacks in Sweida's provincial capital and several villages that killed more than 250 people, mostly civilians.
It was the deadliest attack ever to target the mostly government-held province and the secretive Druze religious minority that populates it.
During the attack the jihadists abducted 36 Druze women and children from a village in Sweida's east, the Observatory said at the time.
Four women had since escaped while two had died, leaving 14 women and 16 children in IS captivity, according to the Observatory.
At the time, another 17 men were unaccounted for but it was unclear if they were also kidnapped.
Local sources say the families of the abductees have been sent photos and videos of their loved ones via Whatsapp.
Sweida had until last week largely remained isolated from Syria's seven-year conflict.
Druze, which made up three percent of Syria's population before 2011, are considered Muslim but IS sees them as heretics.
Eyewitness? Submit your stories now via social or:
Email: eyewitness@pulse.ng
