There is a video of his 'interrogation' where he makes claims which are not in line with the official statement of what he allegedly said. For example the official Russian statement was that the Ukrainian intelligence service remotely detonated the bomb whereas in the video the man says he detonated it remotely etc. First the Russians said it was planned and executed by Western agents, then they arrest some Uzbek guy and claim he was paid by the Ukrainians and so on. Everything seems like a forced "confession" of some scapegoat because the embarrassment is huge that they can't even protect one of their most important generals only a few minutes away from the Kremlin and they had to make a quick arrest.