He was accused of killing 298 civilians after a Russian missile shot down Malaysia Airlines Flight MH17 in July 2014. Mr Girkin also used to brag about ordering prisoners and looters to be shot.
After the shooting down of MH17, Mr Girkin drifted into obscurity but the Kremlin’s invasion of Ukraine in February rejuvenated him and he reinvented himself as a military analyst.
He has criticised the Kremlin, calling its invasion doomed to failure unless it orders a full mobilisation.
Earlier this month, the Ukrainian army recaptured an area around Kharkiv roughly the size of Devon.
“You could say that the battle for the initiative that I have been talking about since June has been won completely by the Ukrainian Armed Forces,” he said. “I am 99 per cent, perhaps 100 per cent, confident in our defeat.”
Mr Girkin had styled himself as a revanchist Imperial Russian officer in 2014, growing a thin moustache and strutting around. Now his face is puffy, his hair has thinned and he has grown a white goatee beard.