MOSCOW — Late last month, a Ukrainian blogger and journalist, Anhar Kochneva, sat on a couch in the place where she was being held by a Syrian rebel group and, as one of her captors filmed her, confessed to working at the behest of Russian intelligence services.

Her friends watched the clip on YouTube with a pit in their stomachs. Though the statement was clearly coerced — she identified a Russian military contact as “Pyotr Petrov,” the equivalent of “John Johnson” — it was the type of recording that could be used to justify an execution.

Urgent negotiations over the fate of Ms. Kochneva, 40, come at a dangerous point in the Syrian conflict, as armed groups with political and mercantile interests turn their attention to civilians. Tens of thousands of Russian citizens and other Russian speakers from the former Soviet Union live in Syria, scattered so widely that even ascertaining their whereabouts is a nearly impossible task.

The danger posed to Russians in Syria has come into increasingly sharp focus since Monday, when armed men kidnapped two Russian steel-plant workers and an Italian colleague not far from the place where Ms. Kochneva was seized. The daily newspaper Kommersant reported that their captors were demanding more than $700,000.