Further on the "murder" of the prisoners.
The Red Cross visited them, see first link, so the position of the prision would be known to Ukraine, therefore I do not believe Ukraine would strike it.
Second shows the prison post strike BEWARE CHARRED BODIES AND CORPSES SHOWN, but I agree with the sentiments it was probably the Russians that did it to hide their atrocities, though the locals said they heard no explosions.. These are simply my views.