"In that case the man could not have cleared out by the front," he said, "as not having the key he could not lock the door after him. Let us see the back door; he may have escaped in that direction."
"The back door was locked," said Mrs. Presk, promptly. "I had the key in my pocket when I went to the lecture."
"Was the door locked when you returned?" asked Gebb, more puzzled than ever.
"Yes, sir, it was. I had no thought that anything was wrong until I came upstairs and saw the corpse; though, to be sure," added Mrs. Presk, suddenly, "I fancied it strange that the lights should be burning so late in Miss Ligram's boudoir. I saw them from the road, you know, Mr. Gebb; and the sight gave me a turn, I can tell you."
"He must have got out through a back window," murmured Gebb.
"Indeed, he didn't, sir. When I brought 'Tilda out of her faint in the kitchen I looked at all the windows in the basement; they are all bolted and barred proper. 'Tilda and me's both careful on account of burglars."
Gebb pinched his chin and shook his head in a perplexed manner; after which he walked to the window of the yellow room and examined it carefully. It was fastened by a snick, the position of which showed that the window was closed, and could not have been used as an exit.
"Let alone the danger of the cove being seen by a chance policeman, and taken up as a burglar," mused Gebb, "what about the upstairs windows, Mrs. Presk?"
"They're all locked, sir. Mr. Inspector examined every one."
"Then the man must be in the house still," was Gebb's final conclusion.