“Oh, yes, you do,” Mason said gently. “You must have known he was dead before you went over to the broker’s, Carl.”
For a long moment, there was tense silence in the apartment. A cheap alarm clock ticked audibly on the dresser. Mattern’s eyes, wide and protruding behind the dark-rimmed spectacles, showed consternation.
Mason said, “I don’t think you killed him, Carl, but I do know that you were interested in that stock transaction. You knew that he was dead before it was time to go over to the broker’s office, and you knew that you had to make it appear Tidings was alive at the time that agreement was concluded.
“You were shrewd enough to realize that if you did make it appear he was alive at noon on Tuesday, the authorities would be forced to fix the time of death as almost immediately after noon, and so you were careful to build up an alibi which would protect you during the afternoon.”
Mattern said, “Mr. Mason, I can assure that I did nothing of the sort. I…”
“Don’t get yourself in bad,” Mason said.
“What do you mean?”
“Simply this,” Mason observed, crossing his legs, settling comfortably back against the chair, and lighting a cigarette. “I’m a mean fighter, Carl.”
“So I’ve heard.”
“In a fight,” Mason said, “I try to damage my adversary in every way possible. I hit below the belt.”