“I was at first puzzled to think of any such mark. And then, during a visit to Mr. Copperdock, the idea came to me. I saw a box full of white bone counters lying on his table, and I managed to appropriate a dozen or so of these. At the same time I carefully noted the envelopes he used in his business, and by a casual question learnt where he had obtained them. I bought three thousand of these, all the remaining stock, giving the name of Mr. Copperdock. There was very little chance of their being traced, but if they had been, the result of inquiries would have shown that they had all been sold to the tobacconist. “I also discovered that the typewriter recently purchased by Mr. Copperdock was a Planet, and I took a careful note of the brand of pen and red ink he habitually used. I next made enquiries among the envelope addressing agencies, until I found one which employed Planet machines. To this agency I sent my envelopes, together with a telephone directory in which I had marked some two thousand names, among which were those of my intended victims who happened to have a telephone. To this list I added one of my own, containing a thousand additional names, among them the jurymen I had not found in the telephone book. I instructed the agency to type these names and addresses on the envelopes. It was a safe assumption that a year later, when I began operations, the agency would not remember having typed the names of the dead men among so many thousands of others. The counters I numbered myself, as required. “Last November, I felt myself in a position to seek my first victim. I decided that it should be Mr. Tovey, a personal friend of Mr. Copperdock, from whom I had learnt all I required to know about his habits. I had, among my other weapons, a paper cutter’s knife, with half a dozen blades. These blades I had sharpened along both edges until they resembled daggers, and I had discovered a means of fixing them lightly into the handle, so that they would remain in the wound, leaving me free to carry off the handle. “That evening, Mr. Ludgrove took his usual walk, returning by way of Paddington station. From here he telephoned to Mr. Tovey, giving him the message that he was wanted at St. Martha’s. Mr. Ludgrove then walked back here, and took on the character of the Black Sailor. Behind this shop is a piece of ground which was once a garden, and that in turn is separated by a low wall from a yard, deserted after business hours, with gates and also a small door leading into a back street. I had made myself a key to the small door, and it provided me with an alternative means of access to this house.