First Culprit: Apenimon Johnson

He has dabbled in chemistry for quite awhile. His motive video showed him owning a research facility that allowed him to legally test these things with his family. The poison used was made by him to be indetectable, painless, and to take about a week for it to work. He needed to test it on someone, as he couldn't before, so he decided to use the killing game as an excuse to do so. After his execution, everyone was shocked, and the gravity of the killing game had set in.

Done