elderly people," Mayer acceeded. "I suppose you inferred from that circumstance that the younger people were taken away alive."
"What other inference could any intelligent person adopt?" Sullivan demanded.
"None," Dan had to admit. "But if this raid was perpetrated solely for the purpose of capturing slaves, why were all the weaklings and elderly persons tortured and killed?"
"Why does a weasel kill ten times as much game as it can possibly use for food?" was Sullivan's countering question. Without waiting for a reply, he went on: "There was a good reason why Zurek was christened the Weasel. His past record indicates that he is a super-sadist. He kills just for the fun of it. Probably gets a kick out of seeing his victims squirm."
"How horrible!" Dan exclaimed.
"Worse than horrible," Jim said. "It's unspeakable. You noticed of course that the bodies were bloated and mangled."
A look of anguish swept across Dan's handsome features and he closed his eyes as if to shut out the frightful sights which still haunted his memory.
"Yes," he almost whispered. "Some of them looked as if—as if they had exploded."
"Only a Martian electrolysis beam gun could have done that," Sullivan declared. "You've heard of them, of course."
"I've heard a little bit about those devilish contrivances, but I can't say I know much about them," Dan admitted. "Why do they call them electrolysis beam guns?"
"Because they shoot out a powerful beam which has an electrolytic action on fluids inside the bodies at which they are aimed. You can readily understand the terrible effect that would produce on a human body."
"You mean it changes the water in the blood into hydrogen and oxygen?"
"Precisely. The pressure of these gases on the walls of the veins and arteries produces frightful torture which lasts until it is ended by a terrible but merciful death."
Mayer uttered an exclamation of horror and said, "But I thought weapons like that were outlawed at the Interplanetary Humanitarian Conference away back in 2734."
"They were, but that wouldn't stop a skunk like Zurek from using them."
"Have you any other evidence that Zurek did this?" Dan asked.
"Plenty!" Sullivan told him. "Here! Take a look at these."
He unfolded his handkerchief and spread it out on the chart-table.
Mayer expected to see some startling clues, such as a weapon, a projectile or an article of jewelry. Instead, the opened handkerchief revealed only a chunk of grey dirt, a wrinkled scrap of colored paper and a piece of curiously bent wire.
WITH puckered brow and opened mouth, Dan stared at these insignificant-looking objects, but he made no comment.
"I found the place where the space-flyer landed," Sullivan explained. "It's about half a kilometer from the village. As you know, every rocket ship leaves distinctive marks in the soil when it takes off. The craft that brought the slavers to Ganymede was of Martian manufacture—a Krovenka to be exact."
"But that doesn't prove that the flyer was manned by Martians," Mayer reminded him. "The Krovenka" is a popular make. They are used all over the Solar System. I
