"The weak point in this theory was the fact that up till then the man had apparently had an unblemished record. However, I set Ainsworth to work, and he very soon dug up a few facts which put quite a different complexion on the matter. He found out that some time ago our respectable friend, who has always had a taste for speculation, suddenly became bitten with the Turf. For the past two years he has been betting heavily with several of the leading bookmakers, and one of them—we know these gentry pretty well at the Yard—confided to us that his own profit in the transaction already amounted to a good many thousand pounds.
"Having got so far, I came more or less to a standstill. I felt convinced in my own mind that, even if Medwin knew nothing about the murder, he was certainly up to some hanky-panky with regard to the money, but it's one thing to believe a man guilty and quite another to prove it.
"It was my interview with Kennedy, and your story coming on top of that, which suddenly did the business. I realized at once, then, that if Miss Seymour was really the Professor's granddaughter, Medwin and Fenton and this fellow Cooper were probably all in the same game. No doubt Cooper had been roped in to help with the burglary, and, although I had no actual evidence that Fenton and Medwin were friends——"
"I could have told you that," interrupted Colin. "I saw a photograph of Fenton on his mantelpiece the day he took me to his house."
"Did you?" returned Marsden. "Well, it's a pity you never thought of mentioning the fact; it might have put me on the right track straight away. As it is, we've had a fairly strenuous thirty-six hours. Our people have been ransacking Cornwall and London to verify the truth of Kennedy's story, and by one o'clock to-day we pretty well completed our case." He laid his hand on the pile. "I have here all the evidence of Mrs. Seymour's marriage and death, and the birth certificate of her daughter. There is no doubt that Miss Seymour was her only child, and she is therefore the sole heiress to the Professor's money."
"I've just a couple of questions I want to ask you," said Colin abruptly. "In the first place, what did these two devils mean to do with Nancy?"
"Marry her to Fenton before she found out the truth. Unfortunately for them, the young lady didn't prove such an easy catch as they expected. I fancy you got most of the credit for that, hence the happy notion of putting you out of the way."
Colin nodded grimly. "And what exactly is your theory about the murder?"
"I haven't the least doubt that it was the work of 'Spike' Cooper. In all probability the other two knew nothing about it. I expect that when he broke into the house the first time—most likely in company with Medwin—he took the opportunity of having a look at the safe. It struck him as being a soft job, and so, without saying a word to the others, he made up his mind to come back again later on and see if there was anything worth collecting. Through some cursed accident the Professor happened to blunder across him, and——"
"But if you know all this," broke out Colin passionately, "why in God's name haven't you arrested them?"