The flash of light,' said Dr. Urth, 'you suppose to be the firing blaster.'

That's certain. The corpse was fresh. Interior portions of the body had not yet frozen. The footprints belonged to two people. Careful measurements showed that the depressions fell into two groups of somewhat different diameters, indicating differently sized spaceboots. In the main, they led to craters GC-3 and GC-5, a pair of-'

'1 am acquainted with the official code for naming lunar craters,' said Dr. Urth pleasantly.

'Umm. In any case, GC-3 contained footprints that led to a rift in the crater wall, within which scraps of hardened pumice were found. X-ray diffraction patterns showed-'

'Singing Bells,' put in the extraterrologist in great excitement. 'Don't tell me this murder of yours involves

Singing 'Bells!'

'What if it does?' demanded Davenport blankly.

'I have one. A University expedition uncovered it and presented it to me in return for-Come, Inspector, I must show it to you.'

Dr. Urth jumped up and pattered across the room, beckoning the other to follow as he did. Davenport, annoyed, followed.

They entered a second room, larger than the first, dimmer, considerably more cluttered. Davenport stared with astonishment at the heterogeneous mass of material that was jumbled together in no pretense at order.

He made out a small lump of 'blue glaze' from Mars, the sort of thing some romantics considered to be an artifact of long-extinct Martians, a small meteorite, a model of an early spaceship, a sealed bottle of nothing scrawlingly labeled 'Venusian atmosphere.'

Dr. Urth said happily, 'I've made a museum of my whole house. It's one of the advantages of being a bachelor. Of course, I haven't quite got things organized. Someday, when I have a spare week or so…'

For a moment he looked about, puzzled; then, remembering, he pushed aside a chart showing the evolutionary scheme of development of the marine invertebrates that were the highest life forms on Barnard's Planet and said, 'Here it is. It's flawed, I'm afraid.'

The Bell hung suspended from a slender wire, soldered delicately onto it. That it was flawed was obvious. It had a constriction line running halfway about it that made it seem like two small globes, firmly but imperfectly squashed together. Despite that, it had been lovingly polished to a dull luster, softly gray, velvety smooth, and faintly pock-marked in a way that laboratories, in their futile efforts to prepare synthetic Bells, had found impossible to duplicate.

Dr. Urth said, 'I experimented a good deal before I found a decent stroker. A flawed Bell is temperamental. But bone works. I have one here'-and he held up something that looked like a short thick spoon made of a gray-white substance-'which I had made out of the femur of an ox. Listen.'

With surprising delicacy, his pudgy fingers maneuvered the Bell, feeling for one best spot. He adjusted it, steadying it daintily. Then, letting the Bell swing free, he brought down the thick end of the bone spoon and stroked the Bell softly.

It was as though a million harps had sounded a mile away. It swelled and faded and returned. It came from no particular direction. It sounded inside the head, incredibly sweet and pathetic and tremulous all at once.

It died away lingeringly and both men were silent for a full minute.

Dr. Urth said, 'Not bad, eh?' and with a flick of his hand set the Bell to swinging on its wire.

Davenport stirred restlessly. 'Careful! Don't break it.' The fragility of a good Singing Bell was proverbial.

Dr. Urth said, 'Geologists say the Bells are only pressure-hardened pumice, enclosing a vacuum in which small beads of rock rattle freely. That's what they say. But if that's all it is, why can't we reproduce one? Now a flawless Bell would make this one sound like a child's harmonica.'

'Exactly,' said Davenport, 'and there aren't a dozen people on Earth who own a flawless one, and there are a hundred people and institutions who would buy one at any price, no questions asked. A supply of Bells would be worth murder.'

The extraterrologist turned to Davenport and pushed his spectacles back on his inconsequential nose with a stubby forefinger. 'I haven't forgotten your murder case. Please go on.' That can be done in a sentence. I know the identity of the murderer.'

They had returned to the chairs in the library and Dr. Urth clasped his hands over his ample abdomen.

'Indeed? Then surely you have no problem. Inspector.'

'Knowing and proving are not the same, Dr. Urth. Unfortunately he has no alibi.'

'You mean, unfortunately he has, don't you?' 

'I mean what I say. If he had an alibi, I could crack it somehow, because it would be a false one. If there were witnesses who claimed they had seen him on Earth at the time of the murder, their stories could be broken down. If he had documentary proof, it could be exposed as a forgery.-, or some sort of trickery. Unfortunately he has none of it.'

'What does he have?'

Carefully Inspector Davenport described the Peyton estate in Colorado. He concluded, 'He has spent every August there in the strictest isolation. Even the T.B.I, would have to testify to that. Any jury would have to presume that he was on his estate this August as well, unless we could present definite proof that he was on the Moon.'

'What makes you think he was on the Moon? Perhaps he is innocent.'

'No!' Davenport was almost violent. 'For fifteen years I've been trying to collect sufficient evidence against him and I've never succeeded. But I can smell a Peyton crime now. I tell you that no one but

Peyton, no one on Earth, would have the impudence or, for that matter, the practical business contacts to attempt disposal of smuggled Singing Bells. He is known to be an expert space pilot. He is known to have had contact with the murdered man, though admittedly not for some months. Unfortunately none of that is proof.'

Dr. Urth said, 'Wouldn't it be simple to use the psycho-probe, now that its use has been legalized?' Davenport scowled, and the scar on his cheek turned livid. 'Have you read the Konski-Hiakawa law. Dr.

Urth?'

'No.'

'I think no one has. The right to mental privacy, the government says, is fundamental. All right, but what follows? The man who is pyschoprobed and proves innocent of the crime for which he was psychoprobed is entitled to as much compensation as he can persuade the courts to give him. In a recent case a bank cashier was awarded twenty-five thousand dollars for having been psychoprobed on inaccurate suspicion of theft. It seems that the circumstantial evidence which seemed to point to theft actually pointed to a small spot of adultery. His claim that he lost his job, was threatened by the husband in question and put in bodily fear, and finally was held up to ridicule and contumely because a news-strip man had learned the results of the probe held good in court.'

'I can see the man's point.'

'So can we all. That's the trouble. One more item to remember: Any man who has been psychoprobed once for any reason can never be psychoprobed again for any reason. No one man, the law says, shall be placed in mental jeopardy twice in his lifetime.'

'Inconvenient.'

'Exactly. In the two years since the psychoprobe has been legitimized, I couldn't count the number of crooks and chiselers who've tried to get themselves psychoprobed for purse-snatching so that they could play the rackets safely afterward. So you see the Department will not allow Peyton to be psychoprobed until they have firm evidence of his guilt. Not legal evidence, maybe, but evidence that is strong enough to convince my boss. The worst of it, Dr. Urth, is that if we come into court without a psychoprobe record, we can't win. In a case as serious as murder, not to have used the psychoprobe is proof enough to the dumbest juror that the prosecution isn't sure of its ground.'