Silence! Do you remember when I helped you on with your overcoat the other night?
I was particular about fitting your arm in.

While doing so I measured your arm with a spring tape measure, from the shoulder to the cuff.

A later visit to your tailor confirmed that measurement.

It proved to be THE EXACT DISTANCE BETWEEN YOUR CHAIR AND THAT DRAWER!" I sat stunned.
"The rest are mere corroborative details! You were again tampering with the drawer when I discovered you doing so! Do not start! The stranger that blundered into the room with a muffler on--was myself! More, I had placed a little soap on the drawer handles when I purposely left you alone.

The soap was on your hand when I shook it at parting.
I softly felt your pockets, when you were asleep, for further developments.