3 He can change his appearance easily.
4 He studied medicine. He could easily cut up a body in the dark.
5 He knows the lanes and yards of Whitechapel well.
6 He can escape from the police because he knows their plans - indeed, he makes their plans.
The arguments against:
1 He spends his life fighting crime.
2 I know my friend. I know he could not do these things.
When I read what I had written, I began to wonder how well I knew Holmes. Did he really fight against crime? He took cases because they interested him, not because he hated crime. It was all just a game to him. He fought crime to amuse himself. It was now late at night. I was terribly tired, but I knew that I had to decide what to do before Holmes came back. Suddenly, as I lay back in my chair, half-asleep, the terrible picture of Holmes cutting up that girl's body appeared again before my eyes. Then, finally, I knew. It was not what I had seen him do, but how he had done it. That look of cool amusement on his face. The way he sang as he worked. The man who could do that could do anything.
Next day I packed my bags and moved into a hotel. That evening I asked Mary to have dinner with me. I told her that I could not sleep while she lived alone in London and the Whitechapel murderer was free to kill again. I asked her to marry me sooner than we had planned. She laughed and said she was not afraid of the murderer. He never killed women like her. But she would marry me as soon as possible, she said, because I looked so worried and unhappy.
Then I wrote a letter to Holmes.
'I am sorry that I cannot welcome you home,' I wrote, 'but I have a reason for that, the best reason in the world. Mary and I are married. She was badly frightened by those awful murders in Whitechapel and will feel safer now that I am by her side.
'It is wonderful to hear from you that Professor Moriarty is dead. Of course I look forward to hearing the full story of his death from you.
'Mary and I are spending a little time travelling. Please write to me at my London club.'
Several days later, Mary and I were married, and we left London. In a quiet little town by the sea, with Mary by my side, I felt strong enough to face the