For perhaps half a minute the Colonel sat staring at him, an expression of mingled incredulity and dismay in his face. Then he said, rather explosively: “Have you any reason for making such a suggestion?”
“Yes, sir, that!” said Hemingway, laying Walter Plenmeller's letter on the desk. “It was found amongst Warrenby's papers—and I should like to know why he took it out of the file, and kept it locked up in a tin-box.”
“Took it out of the file? But that is the most irregular— Good heavens!”
“Highly irregular,” agreed Hemingway. “It's safe to assume he had a good reason for doing it. I'm bound to say I don't see what it was, but I've got a hunch that letter contains the clue I'm looking for.”
The Colonel had picked the letter up, and was reading it. “I remember it well,” he said. “I hold no brief for Gavin, but in my opinion this is a damnable letter to have written! I thought so at the time. In fact, I was extraordinarily sorry for Gavin.”
“It seems to show that his brother hated him pretty bitterly, and I suppose he wouldn't have done that without cause.”
“That's nonsense!” the Colonel said. “Walter didn't hate him at all! What you've got to understand is that Walter was always an uncertain-tempered man, and after he got shot up in the War he used to fly off the handle at the smallest provocation. How much he actually suffered I don't know, and I doubt if anyone did, but he was a real case of nerves shot to pieces. He certainly used to get appalling migraines, and he was always complaining of insomnia. The London specialist he went to prescribed tablets for that. It was established that he took one on the night of his death.”
“He didn't by any chance take a lethal dose?”
“No. Apart from what the post-mortem revealed, the housekeeper—she's there still, by the way—testified that when she dusted his room the morning before, she noticed that only one tablet was left in the bottle he kept on the bedside-table. Another bottle, unopened, was found in his medicine-chest.”
There was a very alert look in the Chief Inspector's face. “So that although he had the means to his hand to commit suicide in the easiest and most pleasant way possible, he chose to gas himself? That seems to me quite an interesting point, sir, if you don't mind my saying so.”