"But I do not see that carries us much further forward as regards Benson," persisted Galloway. "If he is the murderer, as you say, he will clear out as soon as he hears that Penreath is appealing."
"He will not be able to clear out if you arrest him."
"On what grounds? I cannot arrest him for a murder for which another man has been sentenced to death."
"True. But you can arrest him as accessory after the fact, on the ground that he carried the body downstairs and threw it into the pit."
"And suppose he denies having done so? Look here, Mr. Colwyn, I want to help you all I can, but if I have made one mistake, I do not want to make a second one. Frankly, I do not know what to think of your story. It may be true, or it may not. But speaking from a police point of view, we have mighty little to go on if we arrest Benson. If he likes to bluff us we may find ourselves in an awkward position. Nobody saw him commit the murder."
"I realise the truth of what you say because I thought it all over before coming to see you," replied Colwyn. "If Benson denies the truth of the points I have discovered against him, or gives them a different interpretation, it may be difficult to prove them. But he will not—he will confess all he knows."
"What makes you think so?"
"Because his nerve has gone. If I had confronted him that night when I saw him in the room I would have got the whole truth from him."
"Why did you not do so?"
"Because I had not the power to detain him. I am merely a private detective, and can neither arrest a man nor threaten him with arrest. That is why I have come to you. You, with the powers of the law behind you, can frighten Benson into a confession much more effectually than I could."