Mr Healy was originally detained along with his fellow volunteer helper Paul Urey, 45, with the couple accused of being spies.
Mr. Urey appeared on Russian television handcuffed on May 5 and made what appeared to be a scripted statement in which he described the British government as “corrupt”.
Ukrainian officials have already said they will try to involve Messrs. Aslin and Pinner in a prisoner exchange in exchange for Russian prisoners detained by Kyiv.
The death penalty passed on British detainees is believed to be primarily intended as a shock tactic to maximize its value as a currency of exchange.
The verdicts could easily be overturned by Moscow, which has dominated the rulers of the Donetsk People’s Republic and has observed a moratorium on the death penalty since 1996.
This would allow us to see that the Kremlin is exercising clemency, strengthening its hand in any prisoner exchange negotiations.
Two former U.S. military personnel, Alexander Drueke and Andy Huynh, are also detained in the Donetsk People’s Republic after being captured during fighting near the northeastern city of Kharkiv last month.
Drueke’s family said last week that his captors had contacted the U.S. State Department to tell him they wanted to begin negotiations for his release.