It settled quickly, with wisps of wind carrying the particles from place to place. Coming up from the basement Leroy could see out the front window. Everything, the driveway, the lawn, the street, the sidewalk, even the roof, was completely covered with the substance. It looked like a light, fluffy blanket of snow but he knew it was nothing of the sort. If any one thing, it was closer to dust.
The device was conceptually quite simple. Any competent engineer could design such a device, if they had a reason to. It was, after all, basically just a microwave, except instead of being contained and calibrated to violently vibrate water molecules in food, it was directed outward and tuned to the frequency that would rip proteins and DNA apart. Everything alive was built from these tiny pieces, and depended wholly on them. That connection between all life was the key. Of course, something on such a large scale would take a lot of work, and it did. For years he carefully researched and tested, looking for anything that might prevent him from completing his task. But he never found any technical reason why it shouldn't work as he first envisioned it. He knew to accomplish his task would require an enormous amount of energy. For months now he had been storing the power from the electrical grid in a large bank of capacitors which filled the whole of his large basement, along with the emitter itself. The basement was the selling point three years ago when he bought the house, just what he needed.
He walked outside, grabbing an umbrella that was by the door. He wanted to see what he had done. He had to admit, it sure appeared remarkably like snow, even reminding him of playing in it as a boy. But it would not melt, although in time it would slowly disappear, taken away by the wind. It would have been an excellent fertilizer for the seeds that no longer could sprout. The distinctive crunch of snow was absent with each step, it made no noise at all as he packed it down with his boots. He'd walked only a few blocks down along the sidewalk when he noticed that his umbrella was getting harder to hold. The stuff was beginning to cover his umbrella and had an unusual stickiness to it, not easily shaken off. He had walked far enough though, coming to a stop along the sidewalk, peering out and all around his barren landscape.
He had always felt as empty as the world around him would now be. With one final triggering of the emitter he too would be gone, but that would hardly be a change for him. He thought about sticking around, at least for a bit. Naturally there were things he could do: catch up on his list of books to read, watch the movies he'd missed, write some short stories he never got around to. If only he wasn't so weary. No, he thought, better to end it now. With one little push of the remote trigger the device was activated. And thus he became the last warm heap, sheltered under his fallen umbrella.