Then he hastens back to his ambush in the back gardens, and there learns that Smerdyakov is in a fit, that the other servant is ill—the coast is clear and he knows the ‘signals’—what a temptation!
There is no way for him to learn either. He could, possibly, have learned Grigory was out of commission from Smerdyakov but with the valet absent from his usual post there would be no one to tell him.
I suppose he would have noticed that valet missing, but I think Smerdyakov went to bed at midnight.
