What most likely happened is that while Niko was working on the coil, Victor came into the coil lab and went into the booth and turned the coil's power on. Niko wouldn't necessarily be worried about seeing him go into the booth; Victor is the owner of the company, after all, and a fellow scientist. I guess Niko wasn't paranoid enough after all.

Victor's motive was to keep Niko from releasing the plans for free electricity into the public domain, which would benefit mankind in general but would keep Victor and a couple others from becoming spectacularly rich and powerful. Or at least that's what Victor thinks would happen. History suggests that what would really have happened is that he would have made a couple bucks, but very soon someone else would figure out a way to nudge him out of the picture and take it over themselves. Those who discover gold mines don't usually get to keep them very long, she said with bitter smile.