Smathers smiled. "Right — exactly. And left. Just two sides. The Tosoks, on the other hand, have quadrilateral symmetry. Their body parts either come singly or in groups of four. Stant has at least admitted to that much."

"That’s not true," said Ziegler. "They’ve got two arms and two legs, and their eyes come in pairs."

Smathers nodded. "Yes, yes. That’s the way it appears superficially. It’s hard when looking at the product of billions of years of evolution to see the underlying architecture. But let’s consider a hypothetical primitive creature from Alpha Centauri. I suspect it had a body plan like so." He took a lined pad off his desk and drew a large central circle on it with four smaller circles clustered around it, like a cafe table and chairs as seen on a blueprint. "This is a view from above," he said. "The central circle is the animal’s torso. Each of the four circles is the cross section of a limb, looking down from the shoulder. I suspect in early Centauri lifeforms, the four limbs were undifferentiated, and were all used for locomotion — as flagella in aquatic forms, and as legs in land-dwelling ones. You can call these four limbs north, east, south, and west." He wrote the letters N, E, S, and W next to them.

"Well," said Smathers, "you’ve seen that the Tosoks have two arms — one in front, almost like a trunk; and another, more slender one, in back, where you’d expect a tail to be. And they have two legs, one on either side.

Obviously, what happened through evolution is that the east and west limbs became the sole locomotor appendages, and the north and south ones shortened, so that they no longer touched the ground, freeing them up for manipulatory uses.

"A Tosok also has four orifices on the head. Two of the orifices seem to have specialized for breathing, and two more — the ones directly above the arms — have specialized for the intake of food."

"And the eyes?" said Ziegler.

"Right — the four eyes. I suspect they were originally evenly spaced around the head, but over time have migrated together forming two pairs, each of which is capable of stereoscopic vision."

Ziegler nodded, impressed. "All right," she said, "there’s no doubt you’ve got a good handle on the basic physiology."

"As good as anyone can have without ever having seen the insides of a Tosok, yes."

"Then how do you kill one?"

Smathers visibly pulled back. "I— I beg your pardon?"

"If the jury finds Hask guilty, we’re going to ask for the death penalty. We’ll need a way to execute him."

"Oh."

"Well, how do you kill one?"

"I, ah — well, gee, that’s a good question."

"They figured out how to kill our kind easily enough," said Ziegler bitterly.

"We, ah, don’t have the death penalty in Canada," said Smathers. "I don’t know if I’m really the right person for this job."

"My sources tell me you’re damn near the only person for this job. The state of California will compensate you for your time, Professor, but we really do have to know how to kill a Tosok." She smiled at him. "Think of it as a puzzle in science."

Smathers scratched his chin through his white beard. "Well, you can kill just about anything by depriving it of oxygen."

Ziegler shook her head. "It has to be quick and painless; otherwise, t will be deemed unconstitutional cruel-and-unusual punishment. It also can’t be gruesome; the public won’t stand for that."

Smathers considered for a moment. "That makes it difficult. Hanging is out — Tosoks have no necks; having eyes in the back of their heads obviates the need for one. And using either lethal injection or a gas chamber depends on fine details of physiology; I can suggest all kinds of possible poisons, but can’t guarantee any of them will work quickly or without causing pain."

"Electrocution?"

"Yeah, probably — but, again, I can’t guarantee that it’ll be painless or quick for a Tosok."

"Well, I need you to find a way."

Smathers shook his head. "Really, Ms. Ziegler, I—"

"And, of course," said Ziegler, "we would make the corpse available to you after execution." She paused. "It might be your only opportunity to ever study alien anatomy."

Smathers frowned for a very long time, obviously at war with himself. Then, at last, he spoke. "As you know, we don’t have tissue samples or X rays of a Tosok; they’ve been quite shy about such matters. This really isn’t an easy problem." He paused again, then: "Leave it with me, Ms. Ziegler. I’m sure I can work out a method." But then he shook his head and was quiet for a long moment. "I just hope," he said softly, "that I can live with myself after I do."

Dale and Frank were meeting in a restaurant over lunch. Dale was eating a clubhouse sandwich, French fries, and a Caesar salad; Frank was having a grilled chicken breast and tossed salad with fat-free Italian dressing.

"Doesn’t the fact that there are samples of Tosok blood at the crime scene create problems for us?" asked Frank, after swallowing a piece of radicchio.

"Why?" asked Dale.

"Well, if Tosok biochemistry is anything like human biochemistry, the prosecution should be able to get some sort of genetic fingerprint off it to prove it’s Hask’s blood."

"They could only do that if they had samples of the blood of the other Tosoks, to match it against."

"Well, surely they’ll subpoena them."

Dale made a grim little smile. "If they try that, I’ll be all over them like ugly on an ape." He took a bite of his sandwich.

"What? Why?"

The lawyer swallowed, and took a swig of Pepsi. "You know how DNA testing got started?"

Frank shook his head.

"It started in Leicester, England. In 1983, someone there raped and strangled a fifteen-year-old girl. The police couldn’t come up with a single suspect. Three years later, in ’86, the same damned thing happened again: another fifteen-year-old, raped and choked to death. This time, the police arrested a guy named — what was it now? — Buckley, Buckland, something like that. He confessed to the recent murder, but not the one three years before.

"Coincidentally, a British geneticist working right there at the University of Leicester had recently been in the news, because he’d invented a technique for finding genetic markers for disease. He called his technique restriction fragment-length polymorphism; that’s the RFLP they kept talking about in the Simpson criminal trial. One of its incidental uses was that it could distinguish one person’s DNA from another, so the cops called him up and said, look, we’ve got the guy who killed one of the girls, but we want to prove he killed both of them. If we send you semen samples collected from both bodies, can you prove that the DNA in them came from the same guy?

The scientist — Jeffreys, his name was — said, sure thing, send them over."

Frank nodded, and took a sip of coffee.

"Well, guess what?" said Dale. "Jeffreys proved the semen samples both came from the same man — but that man was not the guy who had confessed. The police were furious, but they had to let Buckland go. Now, what to do? How to catch the real murderer? Well, the cops decided they’d ask all male residents of the area between seventeen and thirty-four to submit a blood specimen so that they could be ‘eliminated from the inquiries.’ " Dale shook his head. "Genteel Brits! Anyway, four thousand men came forward, but none of them matched the killer. Eventually, though, they found that a coworker of a man named Colin Pitchfork — the name should have tipped them off, don’t you think? — had donated a sample in Pitchfork’s place. The police took a sample from Pitchfork, who, of course, was the murderer. That was the first case in which DNA fingerprinting was ever used."

"Terrific," said Frank.