Almost as soon as the Reuters interview was published, Mr. Khodakovsky tried to take the comments back, phoning LifeNews, a pro-Kremlin channel in Moscow, to say that his remarks had been taken out of context. Mr. Khodakovsky, a former leader of the government’s Alpha special forces unit in the Donetsk region — who sat for an interview with The New York Times last month — also said that video of the interview, which he possessed, would vindicate him.

Reuters responded by releasing audio of the interview, in which the commander could be clearly heard saying that he was told on the day of the crash that another separatist unit, from Lugansk, had in fact deployed an SA-11 Buk missile system to the rebel-held town of Snizhne, six miles west of the spot where Flight 17 crashed.

“That Buk I know about,” Mr. Khodakovsky told Reuters on Tuesday. “I heard about it. I think they sent it back. Because I found out about it at exactly the moment that I found out that this tragedy had taken place.

“They probably sent it back in order to remove proof of its presence,” he added.