“Hmmph. Some things about you Spacers I never will get used to. I’m sure you’re right, but it still seems more than a little odd to me. ”

“Well, it couldn’t do any harm at all to look into the point,” Kresh said. “Maybe you’re right. Maybe Grieg was used to a house full of people and last night was the aberration. ”

“Mind if I take enough people off traffic duty to check it out?” Cinta asked.

Kresh hesitated a moment. Sandbagged. She had set him up and knocked him right over. The last thing in the world he wanted to do was let her choose what part of the investigation to head up. Suppose this was the very point she needed to muddy up in order to protect herself? How Grieg’s choice of slumber-party guests could possibly matter, Kresh could not imagine, but never mind that. The problem was he could not see any way of saying no to Cinta without flatly stating that he didn’t trust her. And he was far too tired to deal with the twelve kinds of hell that would be sure to kick up. “No, Cinta,” he said. “You go right ahead.”

But even as he spoke, he found himself wondering if he had just made the first big mistake of the investigation.

FREDDA LEVING POINTED her finger at another party guest and watched him disappear. It was a strange sort of game, but one that needed playing. She rubbed her eyes and sighed.

“That’s as many as I can get in this pass. Run it back again, Donald,” she said. “Let’s try that sequence again.”

The integrator’s three-dimensional images scrolled back to the beginning again and started over. Fredda sat and watched as the party guests started to filter into the Residence. By now well over half of the people at the party were missing. Every time Fredda or Donald or the computer managed to identify a person, they would 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.