Jedi knights were here. We couldn't imagine anyone else who could "freeze" the soldiers of the galactic empire so effectively.
Several just like this were left behind as a reminder of sorts of the awesome power they could personally wield.
No other trace of them was ever uncovered. And these "soldiers" never came out of their stupor.
When the force induced ice melted after many years, the "being" inside had metamorphosed into a effervescent image that fluttered away like a butterfly.
These new entities were not captured, nor could they be.
Writing by Regina Stemberger