Only, since Lupin is his bugbear, he's bound to find some means of muddling us up with that wretched animal.

You're going to see Lupin mixed up with all this to a dead certainty, your Grace." The Duke looked at the signatures on the wall.

"It seems to me that he is pretty well mixed up with it already," he said quietly.
"Believe me, your Grace, in a criminal affair it is, above all things, necessary to distrust appearances.

I am growing more and more confident that some ordinary burglars have committed this crime and are trying to put us off the scent by diverting our attention to Lupin." The Duke stooped down carelessly and picked up a book which had fallen from a table.
"Excuse me, but please--please--do not touch anything," said M.Formery quickly.
"Why, this is odd," said the Duke, staring at the floor.
"What is odd ?" said M.Formery.
"Well, this book looks as if it had been knocked off the table by one of the burglars.

And look here; here's a footprint under it--a footprint on the carpet," said the Duke.
M.Formery and the inspector came quickly to the spot.