“You can?”
“Yes.”
“How?”
Mason smiled and said, “I’m not going to disclose my entire hand, Mattern, but remember that you were a bit greedy and a little hasty. Realizing that the stock transaction might be open to question, you were just a little too anxious to get your split from Bolus. Peculiar chap, that Bolus. Rather selfish, I would say. Once the authorities accused him of being your accomplice in the murder, he’d move heaven and earth to show that he was your accomplice only on the stock jobbing deal, and that you alone were responsible for Tidings’ death.”
Mattern shifted his position uncomfortably in the chair.
Mason said, “Thought I’d let you know where I stood, Mattern, that’s all. I wanted to be absolutely fair.”
“What do you want me to do?” Mattern asked.
“Nothing,” Mason said, in some surprise. “Nothing at all. But I just wanted you to know that when it comes time for me to defend my client, I’ll be able to make out a pretty good case against you.”
Mattern laughed and said, “I can’t see what you’re getting at, Mr. Mason. By telling me this in advance, you’ve put yourself entirely in my power. Suppose I should relate this conversation to a jury?”
“No need for you to bother,” Mason said. “I’ll tell them about it myself. Remember, Mattern, I dropped in to tell you that I had reason to believe you knew Tidings was dead Tuesday morning before that stock transaction was concluded. Among other things, I wanted to hear your voice so I could convince myself that it was you who were talking with me over the telephone Tuesday morning. I’m convinced now.”