eliminate his or her image trail from the integrator’s event sequence for the evening.
The imagery integrator was a Settler machine that was a close cousin to the simglobe, designed to take in all manner of visual images and combine then into a single three-dimensional whole. Four dimensions, if you counted time.
And the more people that were missing from its images, the better. They needed to know if there had been anyone who did not belong at the reception, and what better way to do that than by eliminating those who did?
It was a shame that the Settlers’ access recorder system wasn’t useful in these circumstances. It could automatically record comings and goings of each person, and identify each against its access authority list—but such systems were designed to work in more orderly settings than a massive reception. Even the sophisticated access recorder in use at the Residence had been overwhelmed by the crush of bodies at the reception. Too many people, too many strangers, too many people coming in too quickly.
They had fed the integrator everything—the architectural plans of the Residence, all the news video and 3-D imagery taken the night of the assassination, detailed 2-D and 3-D still images of the Residence’s interior and exterior, still pictures of all the guests, and whatever other information Donald had been able to get together.
The integrating simulator had swallowed it all up, and used the masses of data to produce the computer model that Fredda and Donald had been watching for entirely too long. The integrator could present any view of the interior or exterior of the Residence, at any scale, as seen from any point in time in thirty-two hours, the time period under investigation. It could run its imagery forward or backwards at any speed, or freeze it at any point.
It could fill in the blanks from one image by lifting them from another. If, for example, it saw a given man was wearing blue pants and red shoes in a full view from the front, but noted he had a bald spot in a view from the rear where his legs were obscured, it would add both data points to the full image bank of the individual. Given enough information, the integrator could present the man at any time, from any angle—or subtract him from the scene and let you see the woman behind him who had been hidden from the cameras in real life, producing a view of her built up from her image bank. The integrator could not, of course, show what she had been doing while hidden from view, but it could at least show where she had been.
Indeed, much of what the integrator showed was conjectural. Not every part of the reception had been recorded. There had been any number of times and places where there were no camera images, where a certain amount of guesswork was required of the operator. That led to guessing, of course. And guessing made you wonder. What was everyone up to when they were out of view?
And that was the question that made it all turn paranoid. Subject X was seen leaving room A and then appeared forty seconds later appearing in room B, with no video imagery of what went on in the hallway between. Had X moved in the straight-line direction, as seemed reasonable, or had X done something nefarious the moment he or she was out of camera view? Was forty seconds an unwarranted delay, or was it about as long as the trip should have taken? Was the delay caused by some fiendish part of the plot, or by a call of nature, or just a moment’s pause away from the crush of the crowd?
And was it paranoid to ask such questions? After all, someone in that swirl of visitors had killed Chanto Grieg. Several someones had been involved. Somewhere in the evening, someone had to have done something that he or she would not wish to be observed, and presumably had had the sense to do it out of sight of the cameras. Somewhere in all the delays explained by innocent stops in the refresher, and chance meetings in the hallways, the acts leading up to murder were being hidden.
But where? Where in all the background clutter of people at a party were the guilty acts? The best way to find out seemed to be eliminating all the innocent acts and examining what was left.
So here they were, erasing the innocent from the image trail, in hopes of leaving none but the guilty behind.
It was a tricky job, for the integrator images were not infallible, or even completely realistic. If there were imagery, say, from a camera in a hallway that showed a man entering a room that had no camera, the integrator had no way of knowing what the man did once he was out of camera range. Absent instruction from the operator, the simulacrum of the man in the room would just stand there, in the center of the room, a motionless wooden doll, until such time as the hall cameras picked him up reentering the hall. Then the simulacrum would move, stiff- leggedly, toward the door, melding into real-life imagery as the man came back into camera view.
Even stranger were the half people that flickered into existence here and there—half-seen arms or legs or torsos that the integrator was unable to link to any specific person. It did not exclude them until told to do so.
Half of the images Fredda was seeing were at least in part imaginary. The integrator didn’t care. Given the appropriate data, it was quite happy to present hypothetical—or quite spurious—imagery. It could be instructed to run various versions of events, running through all the possibilities of who went where during the moments they were not actually in view of a camera. Even the hypothetical images were useful in sorting out the possibilities.
By now, with more than half the guests accounted for—and thus eliminated—the images were getting more and more surreal. People were talking to other people who weren’t there anymore. What had been tight clumps of people were now isolated twos and threes.
Computers and robots should have been able to do this job, but no robot or computer had ever been good enough at pattern recognition, at being able to see the whole when looking at only a part. Even their thousands of years of development were no match for the billions of years of human evolution. That was why Fredda had drawn this duty along with Donald. She could see the bit of chin, or the fleeting, partially obscured profile, and say it was the same face she had seen twenty minutes before, allowing the integrator to connect two image sequences as one person. Better still, Fredda knew lots of people, and was able to identify any number of blurry faces the integrator was not able to match up with its still image identity file.
It was strange to see it all this way, from this godlike angle, but it was a remarkably useful way to sort out the movements of this person and that. Stranger still to see her own image and eliminate it, to see Alvar Kresh and make him vanish. It made her doubt his reality—and her own.
But should she make Alvar vanish? After all, he was the one who found the body. That in and of itself was a trifle suspicious. Donald had been a few steps behind him at the time. Kresh had not been alone in Grieg’s room for long, but suppose it had been for long enough—and even though it was a point open to interpretation, you could read the fact that Grieg had offered no struggle as a hint that he had been killed by someone he knew…
It seemed absurd—and yet someone had killed Grieg, and as of right now the rest of the universe only had Kresh’s word for it that he had found Grieg dead.
No. It couldn’t be. Not Kresh. The man might be stubborn and infuriating as hell, but there was no more honorable man on the planet. It was absurd to think that a man of his character could have done it. She knew him too well to believe such things. She was reluctant to admit such a thing, even to herself, but she liked him too well to believe such a thing.
Fredda glanced at Donald, seated impassively at the integrator’s control panel. Did fretful, disturbing thoughts like that flit through his mind? Was he troubled by such delusional nonsense? She, Fredda, ought to know. She had, after all, designed his brain, his mind, herself. But that meant nothing at a time like this. The short, sky- blue robot seemed unflappable—but what lurked under the surface? Was he intelligent enough to have doubts, to see that the universe was not the well-ordered, every-peg-in-its-proper-hole place that the Three Laws would make it seem? He was a police robot, after all, and knew as well as any robot in existence what sort of madness humans were capable of.
“Who do you think did it, Donald?” she asked, more or less on impulse. “Who killed Chanto Grieg?”
Donald had been watching the image playback, but now he turned toward Fredda and regarded her with an unreadable stare for a full ten seconds before he replied. “It is impossible for me to say,” he replied. “There is so much information already in our hands, and yet so little of it appears to be useful data. We are forced to eliminate meaningless information as a first step toward the truth.”
“But you are more familiar with the case data than anyone. I know you suspect Caliban and Prospero, but leave them to one side for a moment. Who is your prime human suspect?”
Donald swiveled his head back and forth in an imitation of the human gesture of shaking his head to report uncertainty. “I am afraid I do not, and cannot, have an opinion on that. Before I could get to who, I would have to deal with why, to the question of motive. And I am simply incapable of imagining anyone wishing the—the death of
