"It's an ingenious one, at all events," commented Colwyn. "But would such a careful deliberate murderer overlook the key when he returned?" "Nothing more likely," said the confident superintendent. "It's in trifles like this that murderers give themselves away. The notorious Deeming, who murdered several wives, and disposed of their bodies by burying them under hearthstones and covering them with cement, would probably never have been caught if he had not taken away with him a canary which belonged to the last woman he murdered. It was a clue that couldn't be missed--like the silk skein in Fair Rosamond's Bower." "Here's another point: why did not Ronald, having disposed of the body, disappear at once, instead of waiting for the morning?" "Because if his room had been found empty in the morning, as well as that of Mr. Glenthorpe's, the double disappearance would have aroused instant suspicion and search. Ronald gauged the moment of his departure very cleverly, in my opinion. On the one hand, he wanted to get away before the discovery of Mr. Glenthorpe's empty bedroom; and, on the other hand, he wished to stay at the inn long enough to suggest that he had no reason for flight, but was merely compelled to make an early departure. The trouble and risk he took to conceal the body outside prove conclusively that he thought the pit a sufficiently safe hiding-place to retard discovery of the crime for a considerable time, and he probably thought that even when it was discovered that Mr. Glenthorpe was missing his absence would not, at first, arouse suspicions that he had met with foul play. "It was not as though Mr. Glenthorpe was living at home with relatives who would have immediately raised a hue and cry. He was a lonely old man living in an inn amongst strangers, who were not likely to be interested in his goings and comings. That suggests another alternative theory to account for the key in the door: Ronald may have left it in the door to convey the impression that Mr. Glenthorpe had gone out for an early walk. That belief would at least gain Ronald a few hours to make good his escape from this part of the country and get away by train before any suspicions were aroused. The fact that none of Mr. Glenthorpe's clothes were missing was not likely to be discovered in an inn until suspicion was aroused. Ronald laid his plans well, but how was he to know that in his path to the pit he walked over soil as plastic and impressionable as wax?" "But in spite of that you assume he knew exactly where this pit was situated?" "Nothing more likely. It is well-known to archaeologists. Ronald may well have heard of it while staying at Durrington, or he may have known of it personally through some previous visit to this part of the world. And there is also evidence that Mr. Glenthorpe told him of the hut circles and the pit during dinner last night."