"Check special knowledge and motive then on Dr. Mandel's side. Now, Dr. Urth, picture something else. Whoever it was who confronted Villiers at midnight, saw him collapse, and scanned his paper (let's keep him anonymous for a moment) must have been terribly startled to see Villiers apparently come to life again and to hear him talking into the telephone. Our criminal, in the panic of the moment, realized one thing: he must get rid of the one piece of incriminating material evidence.
"He had to get rid of the undeveloped film of the paper and he had to do it in such a way that it would be safe from discovery so that he might pick it up once more if he remained unsuspected. The outer window sill was ideal. Quickly he threw up Villiers' window, placed the strip of film outside, and left. Now, even if Villiers survived or if his telephoning brought results, it would be merely Villiers' word against his own and it would be easy to show that Villiers was unbalanced."
Talliaferro paused in something like triumph. This would be irrefutable.
Wendell Urth blinked at him and wiggled the thumbs of his clasped hands so that they slapped against his ample shirt front. He said, "And the significance of all that?"
"The significance is that the window was thrown open and the film placed in open air. Now Ryger has lived for ten years on Ceres, Kaunas on Mercury, I on the Moon-barring short leaves and not many of them. We commented to one another several times yesterday on the difficulty of growing acclimated to Earth.
"Our work-worlds are each airless objects. We never go out in the open without a suit. To expose ourselves to unenclosed space is unthinkable. None of us could have opened the window without a severe inner struggle. Dr. Mandel, however, has lived on Earth exclusively. Opening a window to him is only a matter of a bit of muscular exertion. He could do it. We couldn't. Ergo, he did it."
Talliaferro sat back and smiled a bit.
"Space, that's it!" cried Ryger, with enthusiasm.
"That's not it at all," roared Mandel, half rising as though tempted to throw himself at Talliaferro. "I deny the whole miserable fabrication. What about the record I have of Villiers' phone call? He used the word 'classmate.' The entire tape makes it obvious-"
"He was a dying man," said Talliaferro. "Much of what he said you admitted was incomprehensible. I ask you, Dr. Mandel, without having heard the tape, if it isn't true that Villiers' voice is distorted past recognition."
"Well-" said Mandel in confusion.
"I'm sure it is. There is no reason to suppose, then, that you might not have rigged up the tape in advance, complete with the damning word 'classmate.' "
Mandel said, "Good Lord, how would I know there were classmates at the Convention? How would I know they knew about the mass-transference?"
"Villiers might have told you. I presume he did."
"Now, look," said Mandel, "you three saw Villiers alive at eleven. The medical examiner, seeing Villiers' body shortly after 3 a.m. declared he had been dead at least two hours. That was certain. The time of death, therefore, was between 11 p.m. and 1 a.m. I was at a late conference last night. I can prove my whereabouts, miles from the hotel, between 10:00 and 2:00 by a dozen witnesses no one of whom anyone can possibly question. Is that enough for you?"
Talliaferro paused a moment. Then he went on stubbornly, "Even so. Suppose you got back to the hotel by 2:30. You went to Villiers' room to discuss his talk. You found the door open, or you had a duplicate key. Anyway, you found him dead. You seized the opportunity to scan the paper-"
"And if he were already dead, and couldn't make phone calls, why should I hide the film?"
"To remove suspicion. You may have a second copy of the film safe in your possession. For that matter, we have only your own word that the paper itself was destroyed."
"Enough. Enough," cried Urth. "It is an interesting hypothesis, Dr. Talliaferro, but it falls to the ground of its own weight."
Talliaferro frowned. "That's your opinion, perhaps-"
"It would be anyone's opinion. Anyone, that is, with the power of human thought. Don't you see that Hubert Mandel did too much to be the criminal?"
"No," said Talliaferro.
Wendell Urth smiled benignly. "As a scientist, Dr. Talliaferro, you undoubtedly know better than to fall in love with your own theories to the exclusion of facts or reasoning. Do me the pleasure of behaving similarly as a detective.
"Consider that if Dr. Mandel had brought about the death of Villiers and faked an alibi, or if he had found Villiers dead and taken advantage of that, how little he would really have had to do! Why scan the paper or even pretend that anyone had done so? He could simply have taken the paper. Who else knew of its existence? Nobody, really. There is no reason to think Villiers told anyone else about it. Villiers was pathologically secretive. There would have been every reason to think that he told no one.
"No one knew Villiers was giving a talk, except Dr. Mandel. It wasn't announced. No abstract was published. Dr. Mandel could have walked off with the paper in perfect confidence.
"Even if he had discovered that Villiers had talked to his classmates about the matter, what of it? What evidence would his classmates have except the word of one whom they are themselves half willing to consider a madman?
"By announcing instead that Villiers' paper had been destroyed, by declaring his death to be not entirely natural, by searching for a scanned copy of the film-in short by everything Dr. Mandel had done-he has aroused a suspicion that only he could possibly have aroused when he need only have remained quiet to have committed a perfect crime. If he were the criminal, he would be more stupid, more colossally obtuse than anyone I have ever known. And Dr. Mandel, after all, is none of that."