Friends and colleagues of Bassel Khartabil, a Palestinian-Syrian, say they fear he is in imminent danger of a quick military trial and possible execution.
A coalition of his friends and supporters said on Monday that he was transferred from a civil prison to a military prison and denied a lawyer.
The 31-year-old computer engineer was detained in a wave of arrests in the Mazzeh district of Damascus on March 15, 2012.
Since then his family has received no official explanation for his detention or information regarding his whereabouts, according to freebassel.org, an online campaign for his release.
Oussama Al Rafai, Khartabil's uncle who lives in the UAE, told Al Jazeera that his family in Damascus was devastated.
"Family members outside of Syria are in contact with Human Rights Watch and Amnesty International - we are trying to highlight Bassel's situation," his uncle said.
"We still have no contact with Bassel and no lawyer is allowed to see him. We hope that international pressure will help his situation."
"We have received information through friends in Syria that Bassel's health condition is getting worse because of the prison conditions - he is also in very bad physical and psychological shape," Rifai said.
His family had learned from previous detainees at the security branch of Kafr Souseh, Damascus, that Khartabil was first held at that location.
Khartabil was named by Foreign Policy magazine as one of 2012's top 100 thinkers for "fostering an open-source community in a country long on the margins of the internet’s youth culture".
As a computer engineer living in Damascus, his "innovative programming skills helped integrate Syria into the online community".
The prospects of a fair trial are slim in the military prison that Khartabil is believed to be held in now.
Military courts "are composed of military judges and have jurisdiction over crimes committed during wartime and military operations," the Geneva-based International Commission of Jurists (ICJ) said.
"Accused persons before these courts have no right to defence and proceedings are conducted in secret. These courts do not apply existing laws or procedures and their decisions are final, not subject to any form of appeal or review," the ICJ said in a report on Reuters.
Khartabil, also known as Bassel Safadi, launched his career ten years ago in Syria, working as a technical director for a number of local companies on cultural projects.
Since then, he has become known worldwide for his strong commitment to the open web, teaching others about technology, and contributing his experience freely to help the world.