In interviews, more than two dozen Syrians recently released from the Sednaya military prison in Damascus described a government campaign to clear the decks of political detainees. The former inmates said prisoners are being transferred from jails across Syria to join death-row detainees in Sednaya’s basement and then be executed in pre-dawn hangings.

Yet despite these transfers, the population of Sednaya’s once-packed cells — which at their peak held an estimated 10,000 to 20,000 inmates — has dwindled largely because of the unyielding executions, and at least one section of the prison is almost entirely empty, the former detainees said.

Some of the former prisoners had themselves been sentenced to hang, escaping that fate only after relatives paid tens of thousands of dollars to secure their freedom. Others described overhearing conversations between guards relating to the transfer of prisoners to their death. The men all spoke on the condition that their full names not be disclosed out of fear for their families’ safety.