They were given only cursory trials lasting between one and three minutes at one of two military field courts that offered no semblance of judicial process, with sentences typically handed down on the basis of confessions extracted under torture. When the time comes for their execution, the prisoners are handcuffed, blindfolded and led to a basement cell containing 10 stands and 10 nooses.
A former judge from the military court described the executions, saying it would often take up to 10 to 15 minutes for the prisoners to die. "Some didn't die because they are light. For the young ones, their weight wouldn't kill them. The officers' assistants would pull them down and break their necks. Two officers' assistants were in charge of this."
Amnesty said it based its estimate of between 5000 and 13,000 hangings conducted in this way on testimony of 31 former prisoners, four prison officials and three judges familiar with specific instances of the executions and the frequency with which they appeared to occur. They are identified in the report only by their last names because of concerns for their safety.
Amnesty said the executions "amount to war crimes and crimes against humanity" and are authorised at the highest levels of the Syrian Government.
"The horrors depicted in this report reveal a hidden, monstrous campaign, authorised at the highest levels of the Syrian Government, aimed at crushing any form of dissent within the Syrian population," said Lynn Maalouf, deputy director for research at Amnesty International's regional office in Beirut.
The allegations come at a sensitive time for Assad, who is in the process of crushing the nearly 6-year-old rebellion against his rule but still lacks international legitimacy. The findings of the report should be on the agenda for the next round of Syrian peace talks, due to be held in Geneva on February 20, Amnesty said. It also called for an independent United Nations investigation into the atrocities.
The report also contains details of what it calls the "sadistic and dehumanising" conditions under which the prisoners are kept, including repeated torture and the systematic deprivation of food, water and medical care. Many more prisoners die from torture and neglect, Amnesty said.
"Many of the prisoners said they were raped or in some cases forced to rape other prisoners. Torture and beatings are used as a regular form of punishment and degradation, often leading to life-long damage, disability or even death," the report says.
"The cell floors are covered with blood and pus from prisoners' wounds. The bodies of dead detainees are collected by the prison guards each morning, around 9am."