But Poirot cut me short ruthlessly.

"And why would it not be easy? I will tell you, my friend:
Because they are both clean-shaven men. To make up successfully
as one of these two in broad daylight, it would need an actor of
genius, and a certain initial facial resemblance. But in the
case of Alfred Inglethorp, all that is changed. His clothes, his
beard, the glasses which hide his eyes--those are the salient
points about his personal appearance. Now, what is the first
instinct of the criminal? To divert suspicion from himself, is it
not so? And how can he best do that? By throwing it on some one
else. In this instance, there was a man ready to his hand.
Everybody was predisposed to believe in Mr. Inglethorp's guilt.
It was a foregone conclusion that he would be suspected; but, to
make it a sure thing there must be tangible proof--such as the
actual buying of the poison, and that, with a man of the peculiar
appearance of Mr. Inglethorp, was not difficult. Remember, this
young Mace had never actually spoken to Mr. Inglethorp. How
should he doubt that the man in his clothes, with his beard and
his glasses, was not Alfred Inglethorp?"

"It may be so," I said, fascinated by Poirot's eloquence. "But,
if that was the case, why does he not say where he was at six
o'clock on Monday evening?"

"Ah, why indeed?" said Poirot, calming down. "If he were
arrested, he probably would speak, but I do not want it to come
to that. I must make him see the gravity of his position. There
is, of course, something discreditable behind his silence. If he
did not murder his wife, he is, nevertheless, a scoundrel, and