He hoped this blocked any chance of a last-minute convenient "suicide" attempt upon Galeni. Haroche had to be ready by now to move on that plan at a moment's notice; the trick was to deny him the moment. Miles led the rest of his people onward, to Janitorial, where he cornered the department head, an aging colonel. Once the man was reassured that Miles's intense interest in the schedule of air filtration maintenance was no adverse reflection upon his department's services, he became very cooperative. Miles brought him along.

Miles wanted to be in four places at once, but the thing had to be taken in as strict an order as any proof in 5-space math. Inspiration was one thing, demonstration quite another. After collecting a tech from Forensics, he hurried his team along to the sub-sub-basement, and the Evidence Rooms. In a very few more minutes he had his array of impeccable witnesses lined up in Aisle 5, Weapons Room IV. Weddell set his box down and leaned against the shelf frame, arms crossed, his air of skeptical intellectual superiority for once almost masked by his fascination with the proceedings.

Shelf 9 was inconveniently out of reach; Miles had to have Ivan hand him down the familiar little bio-sealed box. His Auditor's seal was unbroken. The two remaining brittle brown capsules waited demurely. He picked up one and rolled it between his thumb and forefinger.

"All right. Watch closely, all. Here goes." He pressed firmly, and the capsule snapped; he waved it twice over his head. A smoky tan comet's-trail of exquisitely fine powder hung a moment in the air, then dissipated. A little smudge clung to his fingers. Ivan was holding his breath, Miles noticed.

"How long should we wait?" Miles asked Dr. Weddell.

"I'd give it at least ten minutes to get all over the room," Weddell advised.

Miles attempted to compose his soul in patience. Illyan stared at the air, his expression hard. Yes, thought Miles, here is the weapon that murdered you. You can't touch it, but it can touch you. . . . Brick-colored, Ivan gave up, and started breathing again before he turned altogether purple and passed out.

At last, Weddell bent down and opened his box. From it he drew a small transparent bottle of clear fluid, and an atomizer dispenser, which he filled. For custom-designing that precious liquid on three hours' notice, Miles was ready to forgive him all his sins of pride for the next five years, and kiss him to boot. Weddell himself seemed to regard it as trivial. Scientifically, perhaps it was. A simple chelation solution, he'd dismissed it. The vector encapsulation's exterior structure is nicely regular, specific, and unique. If you wanted something to detect the presence of the prokaryotes themselves, that would be a real challenge.

"Now," said Miles to the colonel in charge of Janitorial, "we go to the return-air vent and filters."

"This way, my Lord Auditor."