‘I had already spent over three-quarters of an hour and it was nearly one. I took a final look round to see that nothing had been forgotten, and was just leaving the drawing-room when my eye caught a glint of light from the carpet immediately behind the chair in which my wife had died. I stepped over and saw it was a brooch which had evidently been torn from her dress during the struggle. I broke out into a cold sweat as I thought how nearly I had missed it, and realised that its discovery by some one else might have disproved my story and brought me to the scaffold. With no clear idea except to hide it, I put it in my waistcoat pocket, took my hat, and, letting myself out, drew the door sharply behind me. After strolling as far as the Champs Élysées and back, I re-entered with my key. As I had hoped and intended, the shutting of the front door had been heard, and I found the butler obviously uneasy at my wife’s disappearance. I endeavoured to confirm his suspicions that she had gone away with Felix, and, as you know, completely succeeded.
‘Most of that night I spent in my study working out my plans. There was first of all the cask. A cask had been sent me by Dupierre, and it was obvious I must return them an empty one against it or I would give myself away. Where was this empty one to come from?
‘It was clear to me that I must get a precisely similar cask to return, and the only way I could do so would be to order another group, in the hope that it would be sent packed in the same way. But obviously I could not have this group sent to me. The idea then occurred to me that I must write in some imaginary name ordering the statue to be delivered at some place such as a station cloak-room, to be kept till called for. There I could get it without letting my identity become known.
‘But this plan did not please me. I was afraid the police would be able to trace me. I thought over it again, and then I saw that if I ordered it in Felix’s name it would meet the case. It would account for his getting the cask I was sending him, and he would not be believed when he denied ordering it. But I couldn’t give Felix’s name and address, for then he might get both casks, and I would be as badly fixed as ever. Finally I worked out the plan you know. I forged an order in Felix’s hand for the companion group to my own to be sent to Felix at an imaginary address, made a tracing of it, left the letter in Dupierre’s letter-box on Monday night, telephoned them on Tuesday morning ascertaining by what route and train they were sending the group, went to London, met it and had it left in a shed there, all as you must have learnt.’
‘A moment, please,’ interrupted La Touche. ‘You are going a little too quickly for me. You say you made a tracing of your forged order for the companion group and left the letter in Dupierre’s letter-box. I don’t quite understand that.’
‘Oh, you hadn’t found that out, had you not? I will explain. I was in Paris, you see, when I forged the letter. But Dupierre must believe it came to him from London, or his suspicions would be aroused. I met the difficulty by sticking on the envelope a cancelled stamp from a letter I had received from London, copying the remainder of the postmark with a little lampblack. Then I went down to Grenelle in the middle of Monday night and dropped the letter into Dupierre’s box. He would find it next morning all correct with its English stamp, cancelled in a London office.’
In spite of their loathing for this callous and cynical criminal, La Touche and Mallet could not but be impressed by the cleverness of the trick. All the detectives concerned had argued that as the order for the statue had been received apparently from London on Tuesday, it must have been posted there on Monday, and that as Felix was there and Boirac in Paris, the former must have posted it. But how simply they had been duped! Truly, thought the detectives with unwilling admiration, Boirac had deserved to succeed.
‘But the tracing?’ persisted La Touche.
‘I thought that not only must Dupierre believe the letter came from London, but some definite proof that Felix had written it must be provided. I did it in this way. After I had written the letter I made a careful tracing of it on a bit of tracing paper. As you probably know, I visited St. Malo when in London, and there, with Felix’s pen and ink, I retraced over the writing and blotted it. This gave the impression.’
Again his hearers had to admit a rueful admiration for the ingenious ruse. The finding of the impression had seemed so conclusive, and—it was only a trick. And what a simple trick—when you knew it!