In the course of his investigations Mr. Blair had examined the servants at the Moat House. From the footman he heard of the West Indian letter, and of the effect it had produced upon Mr. Marlow. Search had been made for that letter as likely to throw some light on the mystery, but without success. Evidently Mr. Marlow had thought it important enough to destroy. His secret, whatever it might have been, had gone to the grave with him. It was a strange coincidence that the man Brown should also have a correspondent in Jamaica. He it was who had stolen the key of the vault from Alan's desk. Again, Dr. Warrender--who, as his wife told Alan, had been in Jamaica--had been murdered. Between these three men, then--Marlow, Brown and Warrender--there was evidently some connecting-link. Had there not been, Warrender would not have assisted to remove the body of the millionaire, and Brown, by stealing the key, would not have helped him.
"There is no doubt in my mind that Brown was the short man seen by Gramp," Blair said to Alan. "And he was followed from Mrs. Marry's by Dr. Warrender, who was bound on the same errand."
"You mean the theft of the body?"
"I think so. Brown had the key and Gramp saw them remove the corpse."
"He saw Warrender," corrected Alan, "not Brown."
"I judge the other was Brown, from the theft of the key and the fact that Warrender called to see him, and then followed. Again, both men have disappeared--at least, one has. The other is dead."
"And who murdered him?"
"Brown," said the inspector, with conviction. "I am sure of it."
"How can you be sure?"
"Because something unforeseen happened--the murder, probably. In the ordinary course of things, I take it, Brown would have come back to fetch his luggage, and would have gone away in a manner less likely to arouse suspicion. Probably he and Warrender had a quarrel when they put the corpse in the cart. Brown killed the doctor, and then drove away."