You're going to need to be more specific in your question. Time period, who did it, episode? Etc.

In the begging of the forth season, when Pastor Young and the council members died at his house in a fire along with vervain that they had seized.

Pastor Young was manipulated by Shane; however, the vervain specifically was him and the town council making their move against the vampires and removing Liz from duty after Alaric (dark version) outed them. This is the focus of Growing Pains.